favourite riff in a song, you're worst mistake by strung out, the opening riff, once i hear it its always stuck in my head. and for fav solo, probably the bass solo on maxwell murder by rancid, freeman owns.
I don't think my answer will ever stay consistant.
I've just changed my favourite riff to that of Smoke On the Water - Deep Purple. They used to play that out at the speedway over here, apart from the big sprintcars thats all I went out there for, because of that song.