Although I like all shapes and sizes, I do have preferences that I gravitate towards. I tend to prefer slender women (140lbs) down to spinners. On those types of frames, I prefer either Big MMs (D+) or Small Naturals (A/B). C Cups could go either way for me as long as they are firm and responsive.
Yes, MM look great under clothes. But ALMOST every pair that I've have seen have jacked up nips. Plus I can't stand boobs that don't move or that feel rock hard and can't be squeezed.