disclaimer: this is MY BIASED OPINION on each album. When I say "best song" it means "best song for me", even though I know someone else don't like it. I know my opinion is not a fact, just my opinion according to my musical tastes:
Achtung Baby - Not even mildly weak points throughout the album, one homerun after another.
Unforgettable Fire - A couple of really weak tracks for me (4th July + MLK) can't shadow several of the best songs they've made, including 3 of my top 5 songs of all time (Bad + TUF + EPAA). I had to rework the tracklist because I really hated the promenade+4thjuly+bad combo.
Joshua Tree - It has some of their best work, but I'm not a big fan of the TTYW and IGC style even if I don't dislike those songs. A really solid and great album overall.
Boy - Again, another album with no weak points for me. I can't believe this is their first album, it's consistent and yet far from monochromatic. I'm convinced that if a new band released this album right now (2014) it would've been praised to no end as the year's best debut.
---
Songs of Innocence - It's consistent, I don't dislike any song in here, not many really high points.
No Line on the Horizon - Some of their best work of the last 15 years is in here, but is hindered by inconsistence, a couple of weak tracks and bad tracklisting. Imho, it all can be improved through tracklisting, so all in all I ended up ranking it as one of their best works.
Zooropa - An awesome first half and a good but imho inconsistent second one.
HTDAAB - The album is a collection of great individual songs. I'm also blaming tracklisting on this one, which is not really hard to fix.
War - Romantically I think of this as one of their greatest albums of all time... objectively, though, I think that while it has a great first half it also has a rather weak second one. Still a very solid album.
---
ATYCLB - An inconsistent album with some overplayed songs... I like some of those (Beautiful Day) but I never totally enjoyed some others (Stuck). I don't really dislike any track in here (I actually enjoy Grace and Wild Honey), but the inconsistency and a couple of -imho- dull tracks like Stuck and Walk On -I loved it at first- make me not enjoy it as much as I'd like to.
Pop - It has too many songs. It has too many styles. It has too many ideas. Some songs I find them boring (DYFL, LNOE), some songs I really love(Please, Mofo, SATS), and the ones that I love doesn't sound like belonging to the same album. Tracklisting is again heavily to blame, but like I said at first, it has too many songs and actually too many styles.
Rattle and Hum - I'm just counting the 9 studio tracks and I'm even giving it the Silver And Gold studio version to make it 10. Hawkmoon, Heartland, God, Silver And Gold and All I Want is You, are good enough, and I don't mind too much about Desire, Love Rescue Me and Van Diemen's Land, but I don't really enjoy the Angel and WLCTT style.
October - I'll just say that there are some great tracks and some very good demos in here.