You will cause permanent and non-repairable hearing damage/loss if you fire a .44 or .45 without hearing protection. You may not notice it initially, but such things are cumulative.
As to your question, honestly there is very little difference between a 300 grain .44 magnum and 300 grain (or projectiles in that approximate range).45 Colt pushed in the velocity range of 950 to 1050 FPS.
Pick the platform you like the best and go from there.
More often than not, in factory guns the .44 Magnums tend to be more accurate (on average) than .45 Colts. This is due to the fact that many .45 Colt cylinders tend to need to be reamed to a uniform throat diameter. That is not a hard process, and a competent person can do it. Or you can send your cylinder out to have it done, or a good local smith can handle it.
It is hard to beat either one, and once you have a good one, they are very versatile, with the ability to fire loads from very mild such as .45 Colt Cowboy (which is a .45 Colt case cut down to .45 ACP length) to top end loads that border on the 454 Casull. In .44 Magnum, it is the same. You can go from super heavy loads, down to .44 Russian, which is the grandfather of the .44 Magnum, and has recoil in a large frame revolver similar to shooting .38 wadcutters.
Either will work for your needs.
