Slash is still my guitar hero. When he *writes* solos, you can really feel the emotion he puts into them. His impromptu solos aren't that good but you can see that he knows the whole fretboard. He's not just doing scales.
For me, his best guitar solo is Give in to Me (by MJ). Very melodic plus the shred factor.
His phrasing is also very unique. On a single bar he can go from 4:4 to some weird time signature which tabs can't really explain. For example, the last 4-bar run on the last solo on Estrange is tabbed as 4:4 with 16th-note phrases but if you listen to it, it's not just straight 16th notes. There's bits of triplet or quintuplet feels in there that you can't explain.
