LAST EDITED ON Jan-11-11 AT 02:34PM (MST)[p]LAST EDITED ON Jan-11-11 AT 02:30?PM (MST)
I'm very impressed with the .300 WSM as an all around cartridge.
I do not reload either, so I also look for something I can find ammo for. Ammo for the .300 WSM has become nearly as easy to get as the .300 Win Mag and is very similarly priced. It slightly out performs it, with less recoil as well.
Brand wise, there are a lot of decent all around rifles that perform very well out of the box now...several "guarantee" 1"groups @ 100 yards. 2 that stand out as pretty nice to me are the Tikka T3 and the Browning X-bolt (both have detachable magazines instead of drop plates), but others to seriously consider are the Remington 700, Howa, and Savage. The Remington and Howa actions are probably offer the most options as far as accessories are concerned (the newer Remington 700's have an externally adjustable trigger).
I recently acquired a Remington 700 SPS in .300 WSM, but I swapped the stock out for a Blackhawk Axiom. It's a bit on the heavy side, but I really like the adjustabilty of the length of pull (for different shooters, clothing, or shooting positions/situations) as well as the recoil reduction features of the stock. It also looks really cool.
Lastly, above all, I highly recommend you budget and consider higher end optics. There are more expensive options out there (and maybe even some comparable less expensive options), but I am partial to, and have had great luck with, Leupold. Both my big game rifle and my small bore rifle are topped with Leupold VX-3 4.5-14 long range scopes with the B&C reticle. This setup, dialed in, is good to 500 yards. If you want to shoot beyond that you should look into something like their CDS reticle system.