I have one thing against the Glock and that is safety. Much safer concealed carries on the market needless to say (I love my HK P7M8 - you simply CANNOT make an accidental bang without really trying). I have one thing FOR the Glock that I carry with a NY1 trigger and that is it is safer (still not safe enough for me but what the heck) and most important it is reliable as heck. I have five or six Glocks and have never, ever had a misfeed or misfire on any of them; something that I cannot say with my other guns (excepting the revolvers). If I could carry a wee revolver back and forth across the border with me that would be my carry choice I think. Cannot get much safer nor much easier to operate. Only downside for me is 6 or 7 rounds before the reload - ever try reloading a revolver under stress? Not pretty. But if that revolver is in a good holster and the cylinder cannot turn it's pretty safe.
Given my choice I'll go with a .45 ACP or .357Sig. If I have to settle for smaller and lighter I will go with something that is dead accurate and train to take the time to make those shots count. It is the most difficult thing in the world to slow down when you only have six rounds of 357 to make them count... and you CAN do it if you practice enough. Get out there and get the training guys. Center of mass is a fallacy - what you want is center of cardiovascular triangle (a triangle that crosses at the nipples with its apex at the base of the throat). Or if you feel that you've GOT to take the 'dead stop' shot, that's the cerebral cortex triangle shot; which has its base roughly across the lips and its apex and the bridge of the nose - a small target indeed but pretty much a given to have the expected results.
Whatever you carry, make sure that you are comfy with it and well practiced. IPSC/IDPA is a great sport and a great way to compete and get good practice. But you gotta have the training.