My personal choice....
Very early Kimber Compact, steel slide steel frame. Its basically the same size as a Colt CCO ( shorter officers length frame ) with a longer barrel. The Kimber uses a 4" bull barrel, the CCO uses a 4.25" commander style barrel.
It had a factory adjustable rear sight and cut from Kimber. I would not have ordered it new this way, but I replaced the adjustable rear sight with one I modified slightly from Heine.
Though you can buy the Heine sight with a wider notch I didn't think it was worth the extra $25 or whatever. I just did it on the mill and cold blued it.
Pistol choice....
FOR ME, the 1911 platform is ergonomically the best. It just works well for me. It points well, controls are easy to reach and 'natural', etc. I don't shoot the 1911 because its 45 apc. I shoot 45 apc because that is the most common caliber for the 1911. I would shoot a 38 super, 9mm, or 40 without any problem. Its about shot placement for the most part, not the size of the hole.
If I was going to do it over again.....( ie my next toy )
I would buy a Smith and Wesson M&P in .40, in the 'standard' size, not compact. I just don't like the pinky pinch you get with most sub-compacts while changing mags. I have an idea for a bobtail version that I would like to try someday.
As mentioned, you can get a 9mm storm lake barrel for the 40 slide. You can also get a .357sig barrel that is extended and threaded. 357 sig uses 40 cal magazines. So with a drop in barrel and the correct mag you can shoot 9mm, 40, and 357sig. Dollar for Dollar that is GREAT in my opinion. The only thing that would make it better is a 22lr conversion ( which they don't make yet ).
Personally I think the S&W M&P combines the ergonomics of the 1911 with the reliability for a modern polymer pistol like a Glock/XD/Ruger/etc. You can get a version with or without a manual safety like a 1911. If you have both you might want to go WITH the safety for consistency. You can even get a trigger job from Bowie Tactical that makes the M&P trigger VERY close to the feel of a short single action 1911 trigger.
Just a few thoughts, good luck with your purchase.