You really need to go to a range that has rentals (as most do), and try out a wide complement of weapons until you find what you like. You need to start by figuring out which caliber best meets your needs. For me, that is 9mm, which is easy and cheap to shoot, and is an adequate personal defense caliber with the right load. YMMV, but 9mm and 45 ACP are by far the cheapest to shoot, and have the widest array of loads available.
IMO the Sigs are the best DA/SA guns in the world, but if you are looking for a carry weapon there is a lot to be said for the Glock's consistent trigger pull (which is really more like a long-travel SA than anything). I recently did quite a bit of test-shooting with a USP9 Compact and Sig P228 before settling on a Glock 17.
I have big hands and the compact Glocks were too small to be comfy. I liked the grip of the USP, but the trigger is a bit nasty, and other things being equal I am not fond of manual safeties like the USP's. The Sig had by far the nicest trigger but cost $150 more, and I prefer only having one trigger pull to get used to (not to mention the availability of 17-round preban mags). I bet I will end up with some flavor of Sig at some point, though - those guns are a joy to shoot. I have shot a Beretta 92FS/M9 extensively as well but those things are enormous and very heavy for a 9mm pistol.
You sound like a good candidate for a G19 or G23 to me, but to each his own . . .
If budget is a consideration at all you should really look closely at the CZ guns, which are cheap and are arguably right up with Sig and the other nicest-shooting 9mms in the world.
In terms of 45 ACP, there are many, many variations on the 1911, but from a price/performance standpoint the Kimbers and Springfields seem the nicest to me. The Para Ordnance LDA is a neat design as well. Tough not to love the Sig 220 too. These are all pretty spendy guns, though.