Blind Guardian
Katatonia
Opeth
Nevermore
Symphony X
But you know, I always have Nevermore and Symphony X in there, and I don't really know why. I think I like other bands better than them, but I guess I've just liked them for longer. Well, that's not a bad Top 5 by any stretch, in any case.
Honorable mentions:
Devin Townsend and Strapping Young Lad (I can't separate these, sorry)
Soilwork
Anathema
Agalloch
Emperor