Hi,
I reload them both. In my experience, you'll have a much better selection of bullets to work with in .44. I have no trouble finding cast lead bullts for either in common weights, but while I can usually only turn up one weight of jacketed in .45 (225gr., I think?) I can always find every weight from 180 up to 300 in .44.
Of course you have those guys who'll claim the .45 has much greater potential than the .44 and I believe them. But they're using custom guns with oversize 5-shot cylinders. In a stock revolver I think you can improve a lot over factory .45 Colt by handloading, but again in a stock gun you could probably only safely be on a par with the .44.
My opinion, go .44 for the wider selection of bullets...unless you're buying a S&W Mountain Gun, then go .45 because you can work up a nice load that will rival fatory .44 ammo in performance but operate a lower pressure, not pounding the gun or the shooter as much.
That's just my (limited) experience.
Don
Edit: Oh I just saw you're looking at Rugers. Sorry about the Smith comment.
I have a Super Blackhawk in stainless steel. It's launched the front sight several times, next time it comes off I'm drilling and tapping a hole to screw it on with! The grips are loose from recoil (I think, could be shrinkage of the wood) and I am always having to tighten the screw holding the ejector rod on the barrel, even with locktite. Watch that screw, it'll come out and you'll launch the ejector shroud. All in all, good gun. It just gets hammered, that's all. I have a .45 Blackhawk and it's had none of those troubles. But my Redhawk is the best! I'd say think about one of them.
Don