Clothing dictates what I carry. CZ75 in the winter, as small as a Keltec P3AT in the summer when that is as big as I can hide.
Even in the summer though, a big gun is easier to hide than most people think.
Lastly, invest in a good belt (check out Jim the Beltman) and something like a Crossbreed holster and your constant holster purchases will stop. Emphasis very heavy on the belt.