Honestly, neither of them due to the cheap Floyds. They REALLY aren't worth the hassle. I have a very similar RG and I pretty much never play it because of the Floyd. 

Why those two specifically? Budget and location?
At most, I probably change twice a year on guitar, but I do use Elixirs and I can only play for a few hours a week. On bass, it's probably every few months, although I'll throw on a fresh set if I'm recording. Old bass strings sound way worse than old guitar strings.
For what? Why those two guitars?

It's pretty uncommon for a guitar to be outright better than another guitar in a similar price range.
Yes and no. Although it's technically a modelling amp, it plays quite well with pedals in the front. However, I don't believe most of them have effects loops and some effects are much better in the loop than in the front.

For the pedals you wish to use, it should be fine, but it's not exactly what I'd use as a pedal platform.
metal4life71 Tons of shit players scoop their mids. Then the second they play with anyone else, they just vanish from the mix. The guitar is a mid range instrument, mids are vital to a good guitar tone. This is even true in modern metal. Misha in Periphery cranks the mids basically as high as possible (through what's basically a modified 6505, a mid heavy amp), uses a guitar with mid heavy pickups and boosts on top of that.

In my experience, I generally have to cut the bass to stop things being too muddy (and that's what a bassist is for anyway!) and I don't like the piercing highs, so I often cut that a bit too. Then with the GEQ on my Mark V, I cut a bit of the flab in the middle and boost the high mids slightly to taste to make sure I'm still cutting through the mix. 
Defo look at a Variax, you simply won't find something more versatile than that. While it is the top of your budget it would be money well spent.

Honourable mention to a PRS or hardtail Ibanez S series.
 Would absolutely give a nod to a Mesa Mark V here, beautiful cleans and crushing overdrive.
What's your budget and location? There might be other option's you've not considered.

Out of the ones you've listed, I'd go Vyper = Katana >> Orange >>>>>>> Fender for what you want, although I've not personally used the Katana. If you plan on playing with a drummer down the line, the extra wattage of the Katana would probably tip it in favour of that.
H4T3BR33D3R To clarify, the first amp I could get tones that didn't want to make me stop playing on the spot. The Spider 3 is not a good amp by any stretch, although I somehow think the newer ones are even worse. Under no circumstance would I recommend anyone buy one today and I was happy to upgrade even to another cheap modelling amp in the Vyper.
tay12lex And I think you're biased as you own an MG and you don't like people shitting on it. I don't really care about being cool and the first non terrible amp I used was a Spider 3 15w that my mate lent to me. I've been there with the cheap practice amps. When I started, there weren't many other options for metal in that budget. To quote my friend, "you either get a Spider or you splurge and get a 5150. Nothing in between."

That was well over a decade ago. These days, there are tons of pretty solid practice amps in the same price range. The only reason that MGs sell is the brand on the grill. The cleans are okay, but the distortion sounds like a hive. I'm sure you could get something passable with a distortion pedal through the clean channel, but that absolutely puts you in the price range of superior amps.
Quote by tay12lex
Are they though? Are they really that far off from a Fender Champion 40 or an Orange CR30? I don't think so.

Yeah, I'd say so. That Fender is actually a pretty solid all around amp, especially for a beginner.  The Crush is an amazing rock and hard rock amp on a budget. I wouldn't take either of them for metal, although I'd take them over MGs or solid state Spiders any day.
Out of those, the VR15 would get my vote, mostly because of the larger speaker over the others. I find that the smaller speakers sound a bit shitty even just for practicing. I would say that the Katana is insanely versatile though. If possible, I'd see if you could find a Valvetronix or a slightly larger Katana. The Valvetronix would be perfect for you, but it would depend on availability and price in your region. I don't think you could go too wrong with any of them though.
What sort of genre(s) are you looking to play? The Katana and Vyper are solid all rounder's on that budget.
Deadpool_25 I'd honestly put them at the bottom of the beginner amps list. Pretty much every other cheap modelling amp would be better. I do agree there is value for a beginner having a few solid presets they can work from though. I'd take and recommend a Vyper, Katana, Valvetronix or even a Cube over a Spider.
Quote by Deadpool_25
As much crap as people give it (and I have too at times), the Line 6 Spider series (I’d check out the V) does EXACTLY what you want. The downside is that Internet forum tone specialists will say you have a crappy amp. And they’re not wrong...from their perspective. Those amps don’t have the best tone and wouldn’t be a great choice for some gigs, but it sounds good enough and again, does exactly what you want. If you’re going to let internet negativity affect you (which is absolutely understandable imo), then it may not be the best choice as you’ll start to regret your choice.

The Boss Katana line is also a solid option, though it’s easier to quickly access a lot of presets on the Spiders. Blackstar would also get the job done to be honest.

You might also consider that even if you do get something like those that are fairly cheap, there will likely come a time when you want to upgrade. Some will argue that you may as well just get something “better” right off the bat. Not a horrible argument, but consider that by waiting you’re more likely to develop a better idea of what you actually want. Like what if you buy a nice Marshall and later wish you’d have gotten a Mesa? Furthermore, you’re almost certain to upgrade more than once anyway. You opened that door by reading a forum in the first place.

So while there are some potential downsides, the amps I (and some others) have mentioned do what you’re asking for.

The problem with stuff like the Spiders or MGs isn't that they're crap compared to a Helix or JCM800, but that they're crap compared to other things in their price range.
For those, I'd have a look at the Randall RD20
If both amps have effects loops, it's possible. Which two amps are they?
dirkv2234 Sadly, you're gonna have to choose between buying new gear and not getting that tone. The "cheap" version of their live tone is an Axe FX or a Kemper, the expensive version is multiple Mesas, Randalls, Diezels and a fuckton of effects. If nothing else, they were pretty much always using American voiced amps, so the MG is possibly one of the worst amps to try and get that tone on. 

Nolasludge's post will probably get you the closest with your current setup. I'd add that Metallica doesn't use as much gain as you might think, so you might want to drop the gain a tad to keep the tightness. In addition, the bass guitar and double rhythm guitars make up a good chunk of the tone and adds the heaviness, so even with a Mesa, I can confirm you won't get all the way there on your own.
Those sort of strings are insane. I'm running 10-74 on my TAM10 and usually tune down the 8th string to E. Even ignoring the scale difference, to use that in A is crazy.
They used tons of amps over the years, but particularly the Mesa MKIIC+ was a common fixture. These days I'm pretty sure they've moved over to Kempers.
Out of those, I'd probably go with the Yamaha. They're great beginner guitars and are pretty versatile. That said, where exactly are you located? There's a pretty diverse community here and they might be able to find some other options.
All depends on your budget. What you really need is new amp, even upgrading to something like a Katana or cheap Orange would be an improvement. However, even a DS2 would probably be an improvement over your current setup.
Quite simply, use a good camera. The iPhone 4 actually has a pretty decent video camera despite its age, if it's the best you have I'd recommend getting a tripod for it and just switching the audio for the properly produced track in software. 
tay12lex The fact that any of them are better at all kills the MG. There's this horrible fizz to the MGs that just can't be dialled out. I'd specifically say the Orange and Vox amps there are better in every single way than the MGs while the others are better at specific things. The Orange stuff especially works great as budget pedal platforms, since there's no modelling stuff.

I also somehow forgot to mention the Boss Katana in the last post, which also smokes the MGs.
tay12lex For the cost of a small MG + a $50 distortion pedal, you can look at the Orange Crush, a Vox modelling amp, some stuff from Blackstar, Roland Cubes, Fender's modelling amps and for a tiny little bit more, you can get an Orange Micro terror. Even for metal, I'd take ANY of those over an MG and a cheap distortion pedal. For Rock, any of the Orange options or the Vox would be my weapons of choice in that budget.

There's not a single budget or genre where I'd recommend an MG.
tay12lex Thing is for the price of those amps and a decent distortion, you could just get a good amp to begin with, especially with the rise of small amp heads. 
I can't imagine 0 gain would be conducive to a good tone...

Honestly, without knowing the amp and what you're aiming for, it's impossible to say. In addition, it'll be affected by your guitar, your playing, the room you're playing in, your hearing and a whole host of other factors. Play around with the setting and find what works for you.

The only general advice I'd give would be to dial your tone with the volume and tone on your guitar dialed back a tad. It pretty much gives you a controllable boost at your fingertips and can help maintain definition even with higher gain.
If it fits within budget, a Peavey 5150/6505 is kind of the gold standard for that sort of metal. However, the cleans are pretty meh at best. Another one to look at would be the Randall RD20, great distortion but really nice cleans too.
Why specifically a Marshall? What budget? Location?
If you want good cleans, avoid the 6505/5150. That said, it's a gold standard for metalcore. Depending on how the used market is where you are, possibly look at a used Rectifier or Mark series. You could also fit a Kemper and powered cab into that budget.
Especially for metal, I'd consider a good modelling setup in that price range, something like a Helix and powered cab.
No more awkward than playing 6 string songs on a 7. Once you get used to the neck, there's no real problems.
Out of those, probably the Schecter. What's your budget and location? Are there any features you do/n't want on a guitar?
Really depends on what you're wanting to do. I'd say a compressor and overdrive are the most universal though.
That's just using a jack for the footswitch right? If so, pretty much any generic one should work.
For me, I'd get a delay and an overdrive. However, I think delays generally sound like ass going through the front of an amp and an overdrive would't do much for a modelling amp like your Spider.

What you really need is a new amp. Then you need to figure out what you want to achieve.
Define work. You could probably tune up just fine, but they might be really tough to play.
Sounds a LOT like a really distorted bass, not a guitar.
Really depends how your amps channels are controlled. I use a Boss ES8 for this function, although there is a slightly smaller one too. Would be MUCH easier if my amp had MIDI though.
Might be a tiny bit over budget, but a Randall Diavolo might have what you want. You'd want at least the 20w version if you're playing with others. Great distortion, really nice cleans for a metal amp. For portability, you'd want to pair it with a 1x12 cab at most. The head is light and small enough to not be a problem to transport.

For something portable, have you considered a modelling setup? If the spaces you're going to have speakers or a PA, they're a lot easier to carry and more consistent in tone.