45c for sure. the frame ends right at the end of my digits perfectly, so no extra grip sticking out or a pinky extension necessary.
The only thing I'd like is a thinner grip for where the web of my thumb/index sits
45c for me as well.
I was looking at the glock 30 and 36, the gunstore I was in had a used 45c and they let me shoot it at their range. It was so much better than the glocks I brought it home.
The 9c only cause that is what I have & shoot a lot, like the 40c , the FS9. Do not care for BG380. Going to have to try 45c next time i'm at the range.
I only have the M&P 9L (I try to not buy more than one example of any given base-model, just for the sake of variety), but my general affinity for 9mm and longer barrels led me to that purchase this one.