I´m not a guitar player but in my opinion Eddie Van Halen is THE man for all the improvements he´s done on the guitar playing.

Yngwie Malmsteen is fast and a lot technichal, but that´s it. I like Kiko Loureiro (from Angra) much more, but that´s my opinion.

As for compositions, I´d go with Rafael Bittencourt also from Angra. What a great mind he has and what a great feeling he puts in Angra´s songs.

I think feeling is the most important thing so that´s why I respect Richie Sambora so much, he got that.