I love them all as 90s U2 is just about perfect for me (although I love 80s U2 as well). I picked Original Soundtracks 1, because I figured it would get ousted. But I suppose, because of what it means to me and for how long it's been a part of my life, Achtung Baby is tough to beat. That said, Pop has become more and more a favorite over the years. I just love the sound of that record, not to mention that era. But the 90s overall, at least from my perspective, seemed to be a very exciting time to be a U2 fan.