Coldplay, like the sound better, like the lyrics better, the music just suits me more. U2 is an okay band, but not really my favorite. Comparing them, Coldplay hasn't been out in the limelight nearly as long as U2, so it's easy to say one has better albums. U2 has a LOT more to work with than Coldplay does at the moment(Coldplay-'96, U2 -'76). At a time, U2 were pioneers, I don't see it as such anymore, they're just another good band. Music for me doesn't have to be groundbreaking for me to like it, it just has to have a good music, which I consider Coldplay to be. Not to say that U2 is bad, but lately their stuff hasn't been the greatest.
I like that coldplay doesn't have a definite sound. It would get boring after a while, that's part of the reason I lost interest with U2 for some time. Their music wasn't doing anything for me, with Coldplay I expect different things more often than I do with other bands. And they're pretty good at delivering it. It's unfair to compare them album wise, U2 has so many more years on Coldplay. It's easy to say U2 has more good albums than Coldplay has, their number of good albums is probably more than Coldplay's total number of albums to begin with.