Undisputed??? I'd dispute that...
Everybody has their own opinion on this (who is the "greatest") so don't take me too seriously when I say Romeo is the "undisputed" best in the world. He is better than Petrucci though! (Oh boy, now I've gone and said it!)
My list was:
1. MICHAEL ROMEO (undisputed champion of the guitar world)
2. Kiko Loureiro (I've seen some sick sick live stuff from him, fantastico)
3. Alexi Lahio (a true innovator before he became a drunk)
4. Jari Maenpaa (Man does Ensiferum miss him, best solos and sweeps, period)
5. John Petrucci (Romeo rocks him, and DT fans hate it!)
6. Marty Friedman (Master of note choices, Rust in Peace is my favorite)
7. Jason Becker (Along with Marty, Cacophony was the best duo ever)
8. Eddie Van Halen (Brought tapping into the mainstream, Hot for Teacher!!)
9. Jeff Waters (Where is he on everybody's lists? Plays with true soul)
10. Yngwie Malmsteen (He'd be higher up if he wasn't so full of himself)