I would say 1080 on a bright day, if filming at night i would def go for the 720 with the higher frame rate. 1080 requires alot of light to pick everything up. more frames per second with less pixels will give you a better overall viewing i reckon!
I go for 1080p in car - this was shot in 1080 and then scaled down. For exterior shots and other sports I normally go for 720 as it gives you a wider viewing angle (more fish eye).