In reality all three rounds are very similar. However I went with the 458 SOCOM for a couple of reasons;
Bullet construction: The 458 uses the bullets that are widely availible and are designed for use in modern rifles (as opposed to handguns or muzzleloaders). You have the option of using a rapidly expanding 300gr HP all the way up to a 600gr Dangerous Game solid. Also, Barnes just released the TAC-X, which was specificaly designed for the 458S. It has a BC of .268 and will expand down to 1000fps. This was done to theoreticaly extend the rounds operational window out to 440yrds.
Mags: The 458 SOCOM was designed to be used with an unmodified USGI mag. The 450 Bushmaster and 50 Beo required at least a different follower. I routinely use the same mags for 458S and 223 in a given trip to the range.
Headspacing: 458S is able to headspace off it's shoulder, which I like for accuracy and reliablity.
That being said, if you don't reload 458S ammo is a little more pricey. If you do reload, the 458 ends up being a little cheaper.