I built the P-51 twice and the P-38 once. Absolutely love the P-38 and the way it flies, but it was a pain to get it built and it has tons of wrinkles. Of course, it was also the first MS plane I built, so it doesn't surprise me that it happened.
The 1st P-51 I built looked great, but the wing spar broke in it during a turn (the perils of trying to 3D print it in pieces, rather than cutting it out of a piece of plywood, since finding the plywood in stock or at a reasonable price is next to impossible!) and trying to repair it was impossible without destroying the plane. So, I've rebuilt it (and with a better designed spar) and it flies great! Just need to paint it in Red Tails livery.