.45ACP isn't even close to .44 magnum. The .44 would fire a similar size projectile nearly twice as fast, with something like 3x the energy.
Which one to get is down to preference. The .44 (depending on the size of the gun) is gonna have some mean recoil, and be a little expensive to shoot (unless you shoot some cheaper .44 special). .45ACP in a 1911 still has a big boom, but is much more comfortable to shoot. .44 would be better for hunting if you felt like it, but .45 is by no means a weak round.
Basically do you want a revolver, or do you want a semi-auto?
And if you want a revolver, why not start with something a little less hard on the shooter like .357 or .38?
I would choose (and have chosen) the PT1911. 1911 is a fun platform to shoot, parts are REAL easy to find, and in my opinion is just a good looking gun--not to say there's anything wrong with revolvers.