Seems everyone is missing the obvious here... Which pistol do you have, or which one do you want?
Since you're suggesting a first rifle in pistol calibers, especially 2 calibers that allow the utilization of more than one cartridge for target shooting, pumpkin shooting, possibly hunting, and/or self defense, (without a specific preference of your own mentioned), one has to assume you are looking at the future purchase of a pistol to go with the girlfriend's rifle.
The smartest thing to do might be to find someone who has a pistol in each caliber, try them out, and make up your mind which you want to shoot, before buying the rifle. IF you roll your own, you might want to throw the 45 Colt in there as well, as 2MG suggested; if you don't reload, and are basically stuck with factory loads, that may not be a viable option for you.
As was stated earlier in the thread, the 44 mag with full magnum load, can be a little disconcerting for some. It is not by any means, a handgun round for everyone. Speaking from experience however, the 357 with hot handloads can be about as ugly!
Find someone who has both, get together at the range, or out in a vacant field someplace, kill a few rabid pumpkins, and decide which you want to shoot in a handgun, and you'll have the answer to your question on the rifle.