Of that list, Pink Floyd, with the conditions being: 1) I don't like prog rock, 2) the earlier the Floyd, the better, 3) I don't consider them a hardcore, or pure prog rock band...which is probably why they are my pick here, and 4) even though they are considered a prog rock band, the stuff I like the most of theirs is their least "proggy" stuff.
Starting with The Dark Side of the Moon, their albums start getting pretty bad to me. I don't like them at all past Wish You Were Here. To me, there is a slow and steady decline from the first note of their first album, all the way through their career. They're one of those bands. Yes, you know them. The ones who did not at any time get better from one album to the next – only worse. Same with Jethro Tull. Same with Iron Maiden. The Ramones. The list could go on.
Most of those other bands are near-total sonic garbage to me. Prog rock is really the pits of rock to me. It's too damned adult, mature, well behaved, self-serious, [largely] humorless, etc. And it's funny in that while it was deliberately trying to push boundaries and change music – to be liberal and progressive – it actually comes off as extremely conservative and middle-of-the-road compared to earlier forms of rock music. I'd rather hear hair metal (which I absolutely despise, and which drives me up the wall if I have to hear it).
That said, I dig some King Crimson, and a little bit of ELP, though. And I can tolerate Rush's first album. (And I like The Move, which is the roots of ELO).