Let's consider trilogies for U2's albums and rank them according to your preference. These descriptions are mine, so I hope that if you disagree or have anything to add that you change them in your post.
1 - Boy/October/War - their early 80's work exploring their Irish tradition, from the portrayal of youth and celebration to the coming of age through war.
2 - Unforgettable Fire/The Joshua Tree/Rattle and Hum - the band dreams of American landscapes, rock'n'roll and blues, as they mature their political statements.
3 - Achtung Baby/Zooropa/Pop - with media breaking through the old continent, the band takes a turn for the spectacle, exploring European sounds and shuffling messages.
4 - All That You Can't Leave Behind/How to Dismantle an Atomic Bomb/No Line on the Horizon - the band softens their message with personal affairs and polishes their sound for the 00s, assuming a conventional pop/rock stance.
BEST
2
1
3
4
WORST
1 - Boy/October/War - their early 80's work exploring their Irish tradition, from the portrayal of youth and celebration to the coming of age through war.
2 - Unforgettable Fire/The Joshua Tree/Rattle and Hum - the band dreams of American landscapes, rock'n'roll and blues, as they mature their political statements.
3 - Achtung Baby/Zooropa/Pop - with media breaking through the old continent, the band takes a turn for the spectacle, exploring European sounds and shuffling messages.
4 - All That You Can't Leave Behind/How to Dismantle an Atomic Bomb/No Line on the Horizon - the band softens their message with personal affairs and polishes their sound for the 00s, assuming a conventional pop/rock stance.
BEST
2
1
3
4
WORST