The Eagle has my vote. If the incredible kill ratio isn't enough of a reason, then looks and performance are. Sure, maybe the build quality of some airframes isn't up to par and the Pratt and Whitney F100 engine has been troublesome at times, but this doesn't prevent it from being as hard as nails. When it comes to actual combat records and not just egos, training, and talk, the F-15 comes out on top in the air to air role for the Teen Series. The Strike Eagle is no slouch in air to ground either.
Edit: I also have a slight bias, as the F-15 is the poster child of the Massachusetts Air National Guard, which was also the first Guard to receive F-15s.