And nowadays you've got stuff like Doom Metal, Jazz Metal (Shaun Baxter's debut album) and a whole host of other forms and bone crunching metal riffs...
I personally lean most towards the thrash metal (old Metallica, Megadeth, Angra) and Death Metal (In Flames, Iced Earth) and the Doom Metal (Crowbar...) but, I like quite a few "Nu-Metal" songs, I like some of the 80's hair metal songs/bands...so, really it's a case of a decent song more than anything...
And then there's good ol' rock...:D