An easy question for me, since I only own 2 centerfire rifles:
a Winchester Model 70 Super Shadow in .270WSM and
a Howa 1500 in 6.5x55 Swedish Mauser (bought for my boys).
I will keep my .270 Short Magnum for all big game up through Elk and Moose. If it can't be killed with a 140 gr Nosler Accubond or 150 gr Partition, then I shouldn't be shooting it. 3,000+ fps with good sectional density and controlled expansion should do the job.
AS for the other rifle, if it was for me , then I would opt for a nice Varmint rig in .223 remington, probably a Savage with laminated stock. I enjoy shooting varmints and in .223 Remington, the barrels last a lot longer than the 22-250 or 220 swift, and probably last longer with less fouling problems than a .204 Ruger. The nice thing about the .270 short mag is that it can do double duty on long range varmints. The 90 gr Sierra at 3600 fps isn't too bad to shoot and should be quite effective.