The most reliable ? It has to be the Browning High-Power. They last forever. My dad bought one when he first came to Canada in 1967 and he still shoot with it on a weekly basis.
But they're bulky compared to what you can find and according to your CCW needs.
Personally, I'd go with a Walther P99QA (short trigger reset and 6.5lbs pull) and its 3 different backstraps. Otherwise, if you're into deep concealment, the Kahr K9 is probably the best around.