If you don't want to be limited to JJ brand tubes, then check out www.dougstubes.com. Doug is a super helpful guy, like Bob at Eurotubes, and has a great selection of tubes to choose from.

JJ's work great in bright sounding amps, because their tone is a tad on the dark side. But they do work well in a wide variety of amps. If you want a set of power tubes that will really give you a punch on the gut, I'd suggest a set of JJ E34L's (no, that's not a typo, they're slightly differen than EL34's). They're a bit hotter than regular EL34's and have a fatter bottom end. You will need to have your amp re-biased with these though, and it would be a good idea to have it done anyway.