First and foremost, it's about what your preference is. The right gun for one guy isn't the right gun for every guy.

I had a Glock 23 as my LTC gun, but hated the block-of-wood feel to it. Sold it and got an M&Pc in .40. That was the right decision for me. The M&Pc is smaller than the G19/G23, but feels larger in the hand than the G26/G27.