I don't think this should become a jihad to eliminate "inferior" bands. Sentenced is fucking great, for example.
Here are some useful categories:
1. HISTORICAL
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.
3. AESTHETICS
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.
6. POPULARITY
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...)