I prefer the 1911 over the others because of the 3 shots to kill. The rex doesnt like to be fired quickly and gets a little out of hand. The rex might be used more depending on how the 1911 gets tweaked.
The .357 Magnum is a beast if you have a weapon specialization on. The crosshairs narrow to the point where they're almost touching, and you can snipe from the hip at insane distances. After getting a few gold medals on my 1911, and silver on all of them, I was surprised to find myself defaulting to the .357 any time I took a Weapon Specialization. (Yes, they affect secondaries)
other than 1 less shot up close, that's the only statistical advantage the rex has over 1911. Other than close and without magnum, the ttk almost doubles for the rex against the 1911, even the 443 has a faster ttk at far. Honestly the the .357 is more damaging than the .45, but the stats really don't reflect it. Still find it funny that handguns deal more damage than some rifles and smgs.