0% agreed. There is no such thing as an artistic pattern, that U2's oeuvre might be divided into album trilogie. This theory is nonsense.
BOY as the debut album stands on its own, an erratic block. A starting point for the band, U2 do have lookek back a lot in recent years.
OCTOBER is another world: different (religious) topics, sounds that take U2 forward (e.g. "Gloria" being the first time, The Edge uses a slide guitar). Plus the fact, that it lyrically had to be improvised a lot. Unfortunately this album has always been in the shadow of its predecessor and successor. The glorious exception was the renaissance of "Gloria" in '05.
WAR again takes another road: new topics, more politics. If you want to look for cuts in the U2 biography, here is one. Now the most part of the audience sadly only knows the old WAR horses "New Year's Day" or "Sunday Bloody Sunday". Even the reflective "40" has become a live rarity since the 80ies – not to mention the rest of the album, where there are other gems torediscover.
THE UNFORGETTABLE FIRE stand on his own – and has nothing to do with the albums before and afterwards. This recarding the lyrics, the sounds and the way, it was produced and recorded. "Musical landscapes" indeed, a masterpiece in its entirety. And yes folks, maybe the album that stand the test of time for ever.
THE JOSHUA TREE is a closer look to both sides of America: the sunny and the dark side of the moon. In my opinion the highlight in U2's work and Bono's poetical, lyrical approach of songwriting. Take the words to "One Tree Hill" and Bono's (late) commentary to it in '06: "You can't kill poetry!". Exactly.
RATTLE AND HUM – regarding only the new tracks – is not THE JOSHUA TREE II. It is more bluesy, more soul, more rock ("God Part II"). Because of the circumstances it is often held as a "creative failure", but it isn't. These tracks are great, perfectly produced and belong to the best in U2's career. There is no weak one in '88...
ACHTUNG BABY might be the album, where there has been a lot of talk, maybe too much talk about. Unique sounds, a new approach to a more (personal) songwriting – innovvation, re-invention and another corpus of tunes for eternity.
ZOOROPA is more technique, more electronic fooling around, a quick shot produced while on tour. It is a mixture of "old" ("Stay", "The First Time") and "new" U2 ("Lemon", the outtake "Hold Me, Thrill Me, Kiss Me, Kill Me"). A caleidoscope, a snap shot.
PASSENGERS OST VOL. 1 is often forgotten, but still existing. Being too innovative, too radical, too extreme to be labelled as a "correct" U2 album, still all of the four play on the album. And one of the tunes even made it in the setlists '05/'06. An experiment I do like because of the songs/song fragments, but not as a whole. Too arty maybe ...
POP is a step back, but another Exit from the U2 highway towards the direction to find new sounds, new approaches. Often being slaughtered and even neglected by the band now on stage and in books, it still remains one of the most debated albums – and another pure masteriece in my eyes and ears.
MILLION DOLLAR HOTEL might be regarded as another side project, but "The Ground Beneath Her Feet" (with big help by another poet) is one of the U2 gems from the 90ies.
ALL THAT YOU CAN'T LEAVE BEHIND is maybe the first real delusion, I ever felt with a U2 album. It is definetly the collection of songs, I've heard the least in its entirety. The sound is too flat, the lyrics are not the strongest, too – and I still do miss the focus, earlier albums had. It was not a challenge for me to listen to it, it didn't touch me, it didn't hurt. It was o.k. – not more, not less. Though some of the tunes do work fine on stage, I'd like to add.
HOW TO DISMANTLE AN ATOMIC BOMB has nothing in common with its weaker predecessor. Strong tunes, strong sounds, (mostly) finer lyrics – another highlight reagarding variety, but to be a real masterpiece it does miss a focus, a concept, a creative vision, too. Let's see, what the days after the retro-like "Window In The Skies" will bring ...
This is a tricky one... 
Ruin all my fun 
