The crate is gonna be pretty loud. Five watts tube is the perfect practice amp, 18 is close to gig worthy.

EDIT: 5 watts is the perfect SOLO practice amp, if you're talking band practice, then yes the crate would serve you slightly better in terms of volume, though if you're looking to play metal (from the slipknot sig) then the crate won't fufill your needs as far as tone and gain.
well i have pedals and such

which one has better tone? or are they about the same?
That I couldn't say, as I've never played them. I've played the normal valvekings, and they're ok, not brilliant tones but decent and useful. The crate I've never had the chance to play.
I liked the Crate when I tried it. If you eq it right you can have some great cleans. The VK (I didn't use the Royal 8) was just as good but in different ways - hard to put into words. They were both amps that I walked away from saying, "Wow, that was a lot better than I expected". But for different reasons to each. The Super Champ XD would be worth plugging into as well to try.