On some boards i've heard that the BOSS metal zone was good. BUt i bought two years ago and i hate it! i can't do anything with it. Instead i'm using he natural distortion and overdrive on my amp.

I still play metallica, ozzy, pantera, megadeth, maiden, sabbath, testament with a bit of shred (yngwi + petruchi)

But i wouldn't dar use my dang metal zone when playing those songs.