I have to concur with the input of several others... no real reason for a magnum in a "one and only" rifle.
Any of the old standbys like .270WIN, 7-08REM, .280REM, .308WIN, .30-06SPRG are more than adequate for any N. American hunting you'd ever want to do...without the recoil, blast and cost of magnum ammo. Everyone will make a case for their favorite...but in reality there's not really a wrong choice in the batch.
Don't get me wrong, the .300 is a great cartridge....but not really needed in most circumstances. Make that your "second" one and only rifle.
Lots of good advice here and from others. I use a .308 for moose/deer/elk and have never found myself wanting anything different for 400 yards or less, and I simply don't put in enough range time for any further shots. Of course, I'd love to add .300 win mag to the safe one day, but not as a one and done rifle, and certainly not over a classic such as a 270, 308 or 30-06. Everyone has their preferences though. I'll also add a vote for a Tikka. One of the best value rifles out there.