I have a lot of trouble pin-pointing a favorite band, but a band I recently discovered (a little over a year ago, actually) that has become one of my favorites is Four Year Strong. I listen to a lot of different types of music and they combine a lot of the aspects I like from different genres. They have a very upbeat, happy, pop-punk kind of sound with synthesizer and some nice vocal harmonies, but they also have some pretty have guitar and drum parts full of harmonics and double bass.
Some other favorites include Relient K, The Chariot, Johnny Cash, As I Lay Dying, among many others.