At the very least, something to look out for, or a particular brand, since I'm sick and dissatisfied of what I'm getting with just an MG15 and Line 6 Floor pod.

Budget- Willing to spend up to $400-500 for an amp or, less would be preferred.

Genres/Tones- I do play different genres on my own, but I'm a huge fan of the guitar sounds of Suffocation, Iron Monkey, Carcass, Electric Wizard, EyeHateGod, A.C. etc. I'm searching for a heavy sound that doesn't sound digital. The way the cleans sound isn't an issue with me.

I'd most likely be doing jams and sessions, if that counts as "gigging" volumes. I would dive for a used deal at Guitar Center, especially if I can snag a good deal.

The nearest location that any of you can look into the inventory is the GC in North Olmstead, Ohio. I've got some mom-and-pop stores nearby that I can look through, so I'm okay if I can just get a general reccomendation of what brands to look for.

I use an ESP-M-50 mainly that suits me fine, and as I mentioned, I have a Floor Pod, which can hook up to two amps/ amp and cab. If I had to rate myself as a guitar player, I'm no master, but I'm sure as hell not a novice.

Thanks for any help you can give!
dude you seriously need to just completely overhaul your rig, but if you want a general brand to buy go with a used marshall combo amp just stay away from the mg series.
I agree with the above....I'm not familiar at all with ESP guitars, so I can't comment there, but anything from Line 6 is way too digital to use for anything other than convenience at band practice. And Marshall MG's are terrible.

I'd suggest you look into the Peavey Valveking series. They make a 1x12 that's 50 watts, all tube, for $400. I use the the half stack model of that amp, and with my Tube Screamer in front of it for a boost, the gain is great. It's at least worth looking into.