Kevin,
“Lotus Flower” definitely has a nice meaty groove, but I’m not sure I agree that the band has never been sexier. I think you’re forgetting this extremely masculine feat of physical coordination from the “Street Spirit” video:

Okay, maybe not.
Anyway, for my money, “Street Spirit” is the strongest song from Radiohead’s early period. In it, you can see the band dabbling in the more atmospheric and heavily produced sounds that defined their wonderful experimental phase. The song feels forboding and mysterious, with undertones that hint at something even more sinister. It builds steadily, propelled (as all great Radiohead songs are) by a masterful performance from Yorke. I love the way he sings the “strain I am under” part; I can’t think of another rock vocalist who could impart so much pathos to a lyric that’s actually kind of wonky.
I tried my best not to look up any setlists before the concert, but some punk kid told me there was a chance they’d do “Street Spirit,” and when they didn’t, I was pretty bummed.