Ive heard the EL34's have less gain but are better for clean....and 6l6's are better for metal but dont have a better tone...;\
Hmm... someone gave you some innacurate information there.
For the most part, you're not gonna get "gain" from your power tubes, not unless you're cranked to ear-bleed levels. After a certain point on your master volume, you'll realize you're not really getting any louder, just more compressed- and, eventually, more distorted- but this is generally well past halfway on the master.
The vast majority of recorded metal tones you hear are all or almost all preamp distortion. Modern high gain amps tend to have very clean power sections, so unless you're absolutely blasting (we're talking maybe 3/4 of the way up or more!) it's all preamp. Power tube saturation is big and fat sounding, but it's loose and very "classic rock"; it's not a modern metal sound in the least.
EL34s do generally distort earlier and are widely thought to have a more pleasant sounding breakup than 6L6s, which stay cleaner longer and have a brighter or more harsh quality to them when they distort. Since we're probably talking metal here, it's a moot point, really. If you're using the sort of amp that lends itself to power amp distortion- we're talking old-school Marshalls, Fenders and Voxes here; classic rock stuff- chances are it'll sound good (for those kinds of tones, of course) no matter what you're running in the power section.
Generally speaking, 6L6s are thought of as producing better clean tones. They're not as midrangey as EL34s and they do stay cleaner at higher volumes. There are some EL34 amps that have nice cleans; the Bogner Shiva comes to mind, which is widely thought of as having one of the best cleans of any channel switching head- but 6L6s do seem to be preferred for clean tones. Again, it's partly an amp design or voicing thing- no one picks a Recto or 5150, 6L6s power sections both, for their sparkling clean tones.
As for what's better for metal, it's totally up to you and the amp you're using. EL34s have tighter bass and more mids. 6L6s have more and fatter bottom end, as a general rule.
Hope this helps!