Out of that list, my hands down favorite goes to Priest. I literally can not pick a best album by them, because they're all incredible. Even their synth experimentation on Turbo worked for me. They have some of the most inspiring rock anthems ever written.
Maiden comes close, but I think Priest was more metal. Maiden was more about stories and tales, whereas Priest just captured everything rock/metal was all about.
I love early Metallica, but I think they got WAAAYYY too full of themselves and fame went to their heads. That's definitely not metal or what they were about before they got big.
Slayer, to me, is just a gimmick band. Musically, I never thought they were much different then all the other thrash bands, so they used the whole satanic thing as a gimmick to stand out. I would pick Anthrax or Megadeth (or even Overkill) over Slayer, but again, that's just me.
Sabbath was definitely a major influence and helped to shape what rock/metal became, but I'm not quite that old, lol.
And finally, Kiss is good fun rock n' roll, and I do like them, but I don't think they deserve as much credit as they get. They were average musicians at best, but they knew how to make a show out of everything.