I don't think this should become a jihad to eliminate "inferior" bands. Sentenced is fucking great, for example.
Here are some useful categories:
1983-1994 were the years of the growth of a genre. We should document it, all of it.
2. BEST OF
The easy test: would you recommend this to an intelligent non-metalhead? The answer is probably true for about 40 bands.
Are Venom and Mordred important? Yes, historically and in the development of aesthetic.
4. GUILTY PLEASURES
Can I "prove" to you that Von is any good? Who cares...
5. TECHNICAL MERIT
Cynic may be homosexuals who later made a turd of a second album, but their first album is hard to ignore. It's an attempt to apply technical knowledge to metal.
Yes, fuck-me-in-the-ass-with-a-Honda, this is important. Pantera are execrable crap, but they defined much of the history to follow and much of what bands in that time reacted to, whether positively or negatively.
We could say that 3, 5 and 6 are subsets of 1
I think it would be a real mistake to confuse 2 and 4, but most average idiots assume we're doing that anyone. (VON probably belongs in the history section as well...)