For plinkin and deer hunting, any of the available calibers will do fine. IMHO, it really depends on what warms your heart.
.40-60 - kind of an odd cartridge in my view and kind of puny for a big rifle like the 1876. But would be fine for either of your goals. A bit more work to load and not as many bullet choices as the .45s.
.45-60 - easiest and cheapest to load for. Use readily available cutdown 45-70 brass. If you are a beginning reloader, its a good choice.
.45-75 - Considered by many as THE 1876 Winchester cartridge. Pretty close equivelent to the .45-70, but a bottleneck design to make the cartridge shorter to fit the action. Perhaps the best of the bunch ballistically.
.50-95 - exotic, perhaps flatter shooting than the others, but more of a short range cartridge. A bit more expensive to load, but not bad.
When I bought my Uberti a few years ago I went with the .50-95. I just like .50s of all sorts. I'm not a hunter, just a plinker and it does a fine job of plinking. But if I were a hunter, here in the east, it would be fine for the typical ranges we have.
Not much help I suppose, but the takeaway from this is pick whatever makes you happy. I wouldn't let a few dollars difference in reloading cost drive my decision. Once you buy the brass and dies, its all the same.
Good luck!
Steve