Best:
Dressed to Kill. Gene Simmons in high waters. Peter Criss looks as dapper as a man in cat makeup can get. Plus reverse photo on the back - who even knew they had that technology in the early 70s?
(http://members.shaw.ca/amazingone/dressed_to_kill.jpg)
Let's get down to business here. Who best pulls off the look for that cover? Gene obviously comes off the worst on the Dressed To Kill cover, and Paul looks like he's trying too hard to look taller. Is he standing on his toes? I think he is. The cover of Dressed To Kill is an Ace vs. Peter showdown, and I really think Ace wins the day, what with the relaxed foot-up-on-the-pole look and the classic lapel grab. But there's something about Peter's wistful look that makes me want to give him the victory here, since this is probably the only contest where Peter Criss could ever win. Still, gotta go with Ace, the intellectually honest answer.
My favorite KISS album cover:
(http://upload.wikimedia.org/wikipedia/en/b/b6/Dynasty_%28album%29_cover.jpg)
Because it looks like KISS is trapped in the Phantom Zone.
General note: I would have allowed up through Creatures of the Night for the cutoff point, but I agree with the general sentiment that make-up free KISS album covers have no business being discussed in this thread.
Rock & Roll Over and KISS Killers both feature Ace using his laser beam projection powers, and demonstrating that he can fire lasers from not only his eyes, but also his fingers. This makes them great, because they prove that the Space Ace could totally whale on the rest of KISS in a fight at the same time.
Even if Peter and Paul grabbed him by the arms to restrain him long enough for Gene to get in a swing with the Axe Bass, Ace could just melt Gene with his eye beams, and then teleport himself free from the other two and destroy them with his finger lasers. Ace could teleport, right? It seems like something he could do, but it would be hard to reflect this on an album cover. Unless it was a holographic album cover, like Prince's Diamonds & Pearls.
(http://forgottenboy.goldminemag.com/content/binary/kiss_destroyer.jpg)
To balance out my pro-Aceness, he comes off the worst on the Destroyer cover. What kind of leap-into-battle form is that? He's getting in Gene's way. It's almost like he's trying to link hands with him, maybe because Gene has wings and he figures he can glide down into battle with him. Peter, meanwhile, looks like he's just accidentally stepping off that...what is that, anyway? Are they jumping from atop a mound of KISS merchandise? Paul, though, Paul is into it! He's by far the least intimidating of the four - at least the Cat-Man might have claws - but look at that form. Not sure about the look on his face, though. He's either making one of his kissing-faces, or Peter just elbowed him right in the gut.
Disagree about Love Gun being a knock-off of the Destroyer cover. They are similar, yes, but Destroyer is KISS in a post-apocalyptic, 2000 AD future, while Love Gun is KISS in some kind of Robert E. Howard past, only a past where people were all space clowns or super mimes or something.