Worst by far:
Queens of the Stone Age.
Seen them twice - both times were bloody awful. Sloppy, out of tune, not giving a crap.
Best 3 gigs ever in no particular order:
Prince. O2 residency
Hugh Laurie and the Copper Bottom Band - New Theatre, Oxford (I'm not kidding, it was right up there with Prince.)
Pantera - first UK Ozzfest, whenever that was.