There are a few things to consider when choosing between the 44 mag and 480 ruger.
I own both in the Ruger Super Redhawk and will never sell either revolver. BUT, they are two totally different critters in several ways. Things you need to consider to help make the decision that is best for you are:
1. Will you be handloading for your new revolver?
If your a handloader, the difference between the 44 Mag and 480 Ruger are pretty impressive. The 44 is a great chambering, kind of like the 30-06 of the handgun world, will do pretty much anything you could want, do it well and do it for a LONG TIME. The 480 is a BIT more specialized even though you can get bullet weights from 275 clear up to 425 that work well in the 480. You can also get the super bullets for the 44 mag as well if you handload but the larger diameter 480 just handles the heavy weight bullets better and will drive the lighter weight bullets faster then the 44.
2. Will you be hunting with your new revolver? If so, what game will you be hunting?
This may be the most important question in deciding what will be best for you. If you will not be hunting or only hunting big game up to the size of deer, the 44 Mag will do everything you could ever ask for and do it in a wildly common package for ammo choices. If you will be wanting to hunt larger game, the 480 has the advantage with heavier bullets. Not that the 480 Ruger will not work fine on deer size game, it works amazingly well but not needed. If your just wanting a revolver to shoot and not hunt with, the 44 would be the better choice simply from an ammo, component cost point of view.
3. If you will not be handloading, do you want a large selection of factory loads available?
Again, if you will not be handloading for your revolver, the 44 Mag wins hands down with the selection of ammo available for it.
4. Are you recoil sensitive?
The 480 Ruger is touted as offering significantly more energy then the 44 Mag but with the same level of recoil....... Well, I will admit that the 480 Ruger is much easier to shoot then say a 454 but with top handloads in both the 44 Mag and 480 Ruger, you will feel a difference for sure. My favorite load uses the 425 gr Cast Performance bullet loaded right to 1200 fps in the 480 Ruger. My favorite 44 Mag load shoots the 270 gr Deep Curl speer bullet to right at 1500 fps. The 44 mag load inspite of its much higher velocity is really a puff load compared to the 480 load in felt recoil terms.
While the recoil is heavier with the 480, it rolls in the hand much slower then the lighter but quicker slap of the 44 mag load because of the velocity difference.
In reality, it comes down to what you want to do with the revolver and if you handload. IF you DO NOT handload, the 44 Mag is the best choice by far, if you do handload, both can be loaded into extremely flexible options.