Hmmm. Favorite is too hard. Decent songs that spring to mind, won't terrify the entire Elements community, and happen to have a quality youtube link at this moment... I'll dig something up to contribute.
Necrophagist - Fermented Offal Discharge
Even if it isn't your style, at least fast forward to the delicious solo starting at about 3:00.
Helstar - Perseverance And Desperation
Not sure what happened to these guys. This one goes back to 1989, not heavy in case the last one scared you.
Meshuggah - Bleed
You're either into these guy's style, or you're not. I am.
Oh.... hell... while I am here, I'll add a bonus track for obvious reasons.
3D House of Beef - Live Coward, Live
Downtuned, thick, meaty...