Probably my favorite is Kamandi, The Last Boy on Earth by Dave Gibbons and Ryan Sook. They keep Jack Kirby's basic post-apocalyptic boy-meets-Planet of the Apes premise, but reinterprete its aesthetic in a Hal Foster's Prince Valiant-ish vein. The result is the most classic comic strip styled peice of the collection, and simply gorgeous.
The other definitively non-supers strip is Paul Pope's Strange Adventures, featuring (aptly) Adam Strange. For those who may be unfamiliar with Strange, he's sort of a John Carter-ish planetary romance character with more of a Buck Rogers aesthetic. Pope plays up the weird--and the absurd. Check out this wonderful peice of dialogue:
"...Why, they resemble nothing less than the mandrillus sphynx monkey of the family cercocpithecidae...Only huge, blue-furred, and operating strange flying machines. The sight would be patently absurd if it wasn't so horrible!"Indeed. Pope's art is a perfect match for his out-there story:
There are other good strips: Gaiman and Allred's sixties-homage Metamorpho story, Bullock and Heuck's demon-fighting Deadman, and the time travel Flash story makes good use of the format. But there are also several that just don't quite come together--like the Batman and Superman stories, and the Metal Men strip.
The other drawback is the height of the collection itself--at nearly a foot and a half, its too tall for most shelves, at least upright.