I have been making a similar inquiry, and I have another log to throw on the fire. For the same money,the Tikka is actually more accurate, has a far better trigger, and the quality control is much betterthan the other three companies.

Having said that, of the choices you mentioned, if you can get ahold of a pre 64 model 70, grab it and run with it, but you won't get it for $500. Otherwise, the remington 700 ADL is the way to go. I own a Ruger and it shoots well, but the trigger pull is very stiff, and is not easily adjustable. The 700 ADL, with a synthetic stock will be very accurate, and relatively hassle free.

As far as calibers, that is a touchy subject. The hunting you describe sounds perfect for the 308, but I'm partial. The 270 is a great cartridge, and will fill the bill just fine. Good luck.

Workhorse- Hunt hard.