Here's a very nice collection of bloggers writing about U2:
My U2 fandom is more focused on Achtung Baby, when the band went "dark" but also gained Technicolor sound. I was most excited in U2 3D when for the encore the unique guitar chords of "The Fly" started up and the video screens erupted in a thousand colors. You may gather from this that I'm one of those people who actually really like Pop, warts and all. Even Zooropa has its moments for me. So "Medieval U2" is my U2 of choice ... but I'm still excited about a new record coming out, believe me.
Favorite underappreciated U2 song: the B-side "Slow Dancing."
Favorite underappreciated U2 song on an actual album: "For the First Time." (This depends on whether you consider Zooropa an "actual album" or not.)
Favorite band that out-U2's U2: The Violet Burning, specifically on Demonstrates Plastic and Elastic. This is a classic album that shamelessly rips off and mixes up the sound and feel of both Rattle and Hum and Achtung Baby, making it simultaneously familar and new. I think they're better than U2 -- for those who wish U2 had kept in the Achtung Baby phase (anyone? anyone?), this should satisfy.