1-Achtung Baby (my favorite album by anyone)
2-Joshua Tree (simply majestic)
3-Zooropa (U2 at their zenith of creativity and quality as a combination)
4-Unforgettable Fire (Probably the same as Zooropa, only a slight notch behind on my particular list on this drunken eve)
5-War (I think HTDAAB might be better in the long run, but it's much too early to say that)
6-How To Dismantle An Atomic Bomb (can be as high as 3 or as low as 8, it's not old enough yet. )
7-Rattle and Hum (some of the studio tracks are great, overall it's sort of just, good.
8-POP (U2 offers us genius and mediocrity on the same album for the first time, this album is perplexing)
9-ATYCLB (almost boring, basic, a few outstanding tracks, overall much too "safe" for me personally)
10-Boy (energy in youth sparks a few good, if not great tracks and bunch of iffy material)
11-October (2 or 3 good to really good tracks and filler.)
Overall their catalog is quite good, if not great. I don't particularly care for ATYCLB, but there are a ton of people who do. I rank POP kind of low, but I actually think some of it is fucking genius, it's the lesser tracks that bog the album down. Everyone knows that is the most debatable album in U2's history.
But if you look at anyone's list on the whole thread and take the top 5, maybe 6 albums and that is equal to most bands entire careers. Then you add in the rest and you can easily see amongst many reasons why U2 is one of the greatest bands ever.