I'd look at what ammo you can find the most of and buy as much as you'll think you need, along with a box or two of brass here and there if you think you might ever handload again. I think the new 6.8 Western is an excellent round, but suffers because of the poor quality brass its loaded with. Another sleeper is the 6.5 Wby RPM, but you'll need a longer barrel to get the most out of it. Also, I haven't seen 1 box of ammo since right after it came out.
For a short barrel, think something that burns powder faster. That will be .308, .30-06, and probably 7mm-08 good enough. .325 WSM is a good choice, too for that application. Nothing wrong with anything any of the other guys recommended, but to maximize efficiency, you'll need to run a cartridge with faster burning powder unless you don't mind sacrificing velocity at the expense of more recoil.
I got with Dave Manson and "invented" a cartridge to suit my needs using the components I could find in abundance because of this very predicament. That dictates that I handload, however. It gives you many more options. Bottom metal for intermediate length cartridges like the .284 family, 7x57, 6.5x55 CAN BE difficult to find bottom metal for that goes with your action/stock combo. Most bottom metal makers cater to short action cartridges or to magnum cartridges with some coming up in the XM-length but for short action magnum cartridges that still won't work with a standard bolt face. I despise the PRC cartridges because you can't ever find brass or ammo. I think the 6.5 SAUM or 7 SAUM are better options, but perhaps not if you don't handload, as factory loads are tough to find.
Ask yourself how much velocity you stand to lose if that matters, what ammo can you get for the cartridge you choose, and how much of it can you find, and what it will take to get a rifle with your action set up to run that cartridge. Build it in your mind how you'd like it to be, then go see if you can find the parts to make that vision a reality.