Sad to say it,but in my opinion kirk probly has more skill and ability on the fretboard,but slash is much more creative.I can't think of any metallica solo that really hit me except mabey the first few times I heard the solo to "ride the lightning".

a little off the main topic,some of the best solo's ive heard that evoked emotion in me have been fast,well executed solos.Slow soloing can just as easily be boring as a mindless 'wankfest'.

Some argue the its the way you hit the notes that make the difference,but I really think its the note mostly.