Raindrops I was going to say Rend Collective, I love their stuff especially the new album. I'm into Mumford and Sons so it follows - also like David Crowder Band who are similar, more indie in style with folksy and old southern gospel stuff, it's really fabulous and worth a listen to - try their newer album Give us rest
I like Gungor, Starfield, Casting Crowns, Switchfoot (a bit more rocky in feel with country style riffs), some Matt Redman/Chris Tomlin/Hughes et al, though find all that gets a bit samey (apart from the most excellent 10,000 Reasons of course!)
I like Owl City for a different more techno sound, lyrics not overtly Christian but the band members are and there are some gems in there.
Would second Hillsong Utd 'Zion' - was getting a bit bored of the whole Hillsong sound, but this is a welcome departure - really refreshing with great lyrics and some genius eighties-esque sounds. 'A million suns' is particularly memorable.
I like Newsboys and YFriday for a more mainstream sound.
Sure I will think of some more....if I could choose one to go for, I'd say the David Crowder one.