Good question! That's tough because it keeps changing..I think they are all awesome in their own way...but I'm going to say right now:
1. Joyful Rebellion - You have to listen to this start to finish. The progression through the different styles, I really love it.
2. Atlantis Hymns for Disco - this is a CLOSE second and on any given day first. Most of the songs I feel are the true gems I'm almost sure you've not heard, as they weren't singles. Born to Run, Black Ice, CatDiesel. Mirror in the Sky.
3. Exit - As a debut album goes, this ranks up there as one of the best by any artist, imo. Not because it produced 6 hit singles, it didn't...but it gave strong indication that this was going to be an artist who would be following up with some brilliant shit. He didn't disappoint on that count, either, with Joyful Rebellion. Strong, eclectic. The only slightly detracting point was the inclusion of somewhat similar themes/continuations on a couple of the songs, but even then they are different enough to not be an issue. He didn't do this on subsequent albums. My son and I listened to it in the car the other day for the first time in a good while and he said 'man, how many artists make an album this good on their first try?'. Pretty cool.
4. Yes! <- now...bear in mind I haven't heard it all and some songs haven't sunk in fully yet. I replayed one yesterday a few times because I thought it was brilliant in the complexity of the different instrumentation and I wanted to soak it in. I fully expect that Yes! will climb up the list...but then that means another album has to move down the list...gah!
I have to say though that listening to a single or two might get one interested...but it's plopping the CD in and letting the story unfold through each song as the album progresses that really brings it out.
I honestly don't think U2 has heard these albums yet. It just seems like music they would like, I don't know why I think that really..I just do. The combination of brilliant musicianship, rock and reggae tinged melodies, true b-boy styles coupled with a genuinely listenable singing voice that he deftly transitions back and forth to from the rapping...Maybe I'll send a care package their way, they need to hear it!