Piano was my first instrument, and it makes a WHOLE lot more sense to my brain than the guitar does, everything being spread out all flat and easy like, yet I find it WAYYYYY harder to sing and play piano at the same time, so ... guitar it was. Though it took a damn long time to figure out what the deal was with the notes/chords. It still doesn't make sense to my brain, it's just that I've memorized where the fingers have to go. Muscle memory.