Classic death metal and thrash metal.
There are some bands you just can't let go because they're so dammed good... I'm not just talking about the really well known heavy metal bands back in the day. My favorite bands are the most unknown ones. An example of some GREAT death metal from the day is Morbid Saint. They only released one solid studio release that I'm aware of, which I was lucky enough to find a copy of. Their album 'Spectrum of Death' is a classic release and is a must have for any classic metal fan. In the same vein, my absolute favorite early death metal band is Morbid Angel (Yes, it's a different band than Morbid Saint). Their best album was their first, 'Altars of Madness,' which included some of the most sic riffs I've ever heard.
Of these old bands are thrashers, which are still among my favorites. Some examples of some excellent old school thrash: Gammacide, Celtic Frost, Exodus, Anthrax, Slayer, Sanctuary, Testament and Carnivore.
