Taste is taste, as you said; I can quibble about the order, maybe, but the only name I'm like "why is he here?" is Cobain. I think he's a zero, I really do. As for Weiland, I LOVE him, don't get me wrong, and I wish Velvet Revolver was still a thing, but while he's quirky and weird, he wouldn't even be considered for my list either.
1) Freddie Mercury
2) Robert Plant (he's almost hurt by the fact he's a cliche at this point, but in the day, he WAS the "rock god")
3) Bruce Dickinson
4) Paul Stanley
5) Bono
6) Paul McCartney
7) Paul Rogers
8) Rob Halford
9) Steven Tyler
10) Phil Collins
Robin Zander, Roth and Jagger all deserve to be there, I just don't have enough space.