Going through this thread, I'm really beginning to feel like a old fart. Most of my favorite metal acts are the older dogs like Black Sabbath, Deep Purple, Blue Oyster Cult, Alice Cooper, AC/DC, Mountain, Motorhead, Rainbow and Uriah Heep (although calling Heep "metal" is a bit of a stretch). I do like some 80s and 90s acts like Judas Priest, Rob Zombie, and Monster Magnet. Also some lesser-known 00s bands like Priestess and Wolfmother (even though all they do is rip off other bands riffs, but somehow make it interesting).
Right now though, probably because I grew up listening to prog-rock, I'm still finding a great liking to bands like Blind Guardian, Heidevolk, and to some extent Nightwish. Also, Lordi is a fantastically wonderful band as far as I'm concerned.
And, of course, a special shout-out to Clutch, which is my musical lifeblood.