Personally, i think Matt Heafy and Corey Beaulieu are much better guitarists than Herman Li and Sam Totman.
forgive me if i disagree with you there. while they're not as good as the media makes them seem they are quite good, and just fun to listen to. however, my top three would be:
Marty friedman
jason becker
nicolo paganini
he was actually a classical guitarist as well, and his guitar compositions could be just as brutal as his violin. he just wasn't as well known for it as he was violin. i actually think that he got some of those insane arpagio runs on violin from guitar arpagios.