I'm a Model 70 guy through and through, but in my honest opinion the Ruger will be more accurate. The Model 70s are what I call "hunting accurate" in that they're very consistent 1-1.5 MOA guns. Rugers, on the other hand, are very accurate in general and most are easily sub-MOA capable with a variety of loads.
My Model 70 Safari Express in 416 Remington Magnum is sub-MOA with almost everything I put through it as funny as it is for it being a safari rifle. My Extreme Weathers which were in 300WM and 7mmRM, respectively, both shot sub-MOA with Hornady ELD ammo, but they struggled to get under 1 MOA with just about everything else I put through them. I also had a Ultimate Shadow in 300WM and it was the same story. Consistently 1-1.5 MOA, but seldom did I ever get a group under 1".
On the other hand I had a RPR Magnum in 300 Win Mag for a bit and I shot a 5-shot group with it at 200 yards that was 5/8". I shot 5 different factory loads through than gun and only one was ever over 1". I never had a group larger than 1 1/4".
The overall fit and finish on the Model 70 is better, but Ruger makes the better barrels IMO. Both guns have cold hammer forged barrels and will last a long time. The M70 barrels are made for Winchester by FN, and Ruger makes their own barrels obviously.