Boy - simple image that perfectly fits the freshness and innocence of the album.
JT - not my personal favourite but the whole desert imagery is undeniably iconic and striking.
AB - love the colours and the mish-mash of edgy, interesting images. It's very much a cover art of its day but I think it still looks fresh and exciting even after all those years; by comparison I don't think that either Zooropa or POP covers aged that well.
ATYCLB - can't really pinpoint what I like about the cover but I just find the whole image of the band waiting in an airport very evocative.
October cover is easily the worst IMO. Godawful band photo, dated typography. I also don't like the HTDAAB cover at all; Bono's image especially gives me a weird unpleasant impression that someone transposed his head from another photo.