If we are speaking just of "macaroni," then I would have to say my favorite would be, of course, mac and cheese. Homemade is the best of the best made with provolone, cheddar, jack and mozzarella. Oh yum. But sometimes I am to lazy to grind up all that cheese and will resort to just using the prepackaged Velvetta mac and cheese.
Now if we are speaking of pasta in general, spaghetti would head my list (although I do use macaroni a lot of times as it is not as messy when eating as trying to twine spaghetti noodles around a fork.)