I quite like progressive metal.
Seltzer's list is excellent.
I would especially recommend Pain of Salvation, Spiral Architect, Devin Townsend, Spastic Ink(these guys are crazy) & Maudlin of the Well. Actually, F*ck it and listen to them all
Anyways, just a few more suggestions-
Fates Warning - A Pleasant Shade of Grey
Choosing between this and Parallels is so damn annoying. Epic and awesome.
Psychotic Waltz - A Social Grace
Weird, obscure, complex stuff. The vocals add even more to the weirdness. Definitely something i don't come across very often.
Shadow Gallery - Tyranny
An amazing concept album with superb melodies, mindblowing guitar work(and i really mean it) backed with excellent keyboards. Sounds even a little bit power-metallish at times, but tbh, I think that's a good thing here.