I own and have carried two Glock model 21's for the last ten years of my LE career. So I am biased, I would strongly suggest the Glock. I have never had a malfunction out of either of mine, that I didn't cause. Yes the Glock will viod your warranty if your shooting handloads and cast is also a no no. But an after market button rifled barrel with a fully supported chamber. will fix that. The Glock has a polyagonal rifleing, they do not like lead, and just like many other semi auto pistols the chamber is not fully supported, that is what lead to the issues with handloads.
A handgun is a very personal choice it has to fit you and your hand. But saying that the department I retired from had fifty sworn officers when we changed from the S&W 686 to Glocks I was one of the officers who evaluated and selected the new issue handguns. The XD was on the market but was a Check import at the time and was not even a consideration. We evaluated the Glock, S&W, Sig, And a couple others. Sigs were just to expencive. S&W has a Magazine safety so the pistol will not fire with the Mag out or even if it is not locked in the pistol. In the end we chose the Glock in either 40 S&W or 45 ACP. I chose to buy two consecutive pistols so I still have them even though I am retired. Out of the fifty sworn officers ten chose the 45ACP. I am fairly big with large hands 6'03" the forty S&W seemed small to me plus at that time the 40 was a pretty new round and I felt it had not been proven sufficiently. Of the other nine officers that chose the 45 ACP seven were average size men, two were small female officers. It still gripes me a bit because one of the females had consistantly better range scores than ANY MALE OFFICERS with her great big Glock 21 45 ACP she barely made the hight requirements to be hired, 4'11" and very small statured. So as far as the Glock being to large you really have to try one. try to get to some place where you can put a hundred rounds through it and any others your interested in. That wide grip has several advantages the main one is a lot less felt recoil. The Glock is the softest shooting full sized 45 ACP on the market. I have thought about getting a G 30 since they came out but haven't because the G21 works for me, but that is me. If you are wanting a pistol for CCW you need to look at your stature and the way you dress normally, and ask yourself if you can effectivly hide a G21? That may or may not be a consideration. For me they worked fine in uniform, a suit, or in casual wear but like I said I am sort of a big guy.