Still listening to Some Nights. Seriously, I think fun. may be one of the best artists I've listened to. They have this sense of infectious joy that makes it nearly impossible to be in a bad mood when listening to their music.
I hadn't listened to any of their stuff before Some Nights, so I recently gave Aim and Ignite a listen over on Spotify. It's more subdued and less grandiose than the theatrical, bombastic Some Nights, but I love it almost as much - songs like Light A Roman Candle With Me, The Gambler, All The Pretty Girls, and Be Calm are just absolutely joyous to listen to (particularly The Gambler - I have a soft spot for wonderful piano music). The whole album is just fun.
Some Nights is still better, though, and I highly advise giving it a listen.