In terms of voice... I think it's important to have a singer that has a voice that translates well from studio to the live shows... I'm always a little uneasy when I go see bands with singers that are more of the "singer" brand... or have a very distinct or harsh sound... ala Axel Rose. I saw Shinedown last summer... the guy actually sounded better live than on the recordings... I saw Alter Bridge live last spring... That guy was all over the place and didn't sound anything like the recordings... maybe it was a bad night?? But that's kind of what I mean... If you have an awesome voice for an hour or so... then it's shot... It doesn't mean much. I think a distinct tone to the voice is important as well... i hate hearing bands with good instrumentals but with a middle of the road... dime a dozen vocalist...