Tough choice. I have 2 Mauser's, and 3 Mosin Nagants. Accuracy is great for both, I get a 1 inch group at easy at 50yds with the Mauser's, and consistantly hit 6 inch plates at 300 yds with the Mosin's. One of my Mosin's is even a certified sniper.
The Mauser's action is a little smoother, has a bent bolt, safety is good, and it doesn't let you bolt if there isn't any rounds left. Mosin's safety is awful, has a straight bolt, and the trigger is a little heavy.
Don't get me wrong they are both great rifles, but I am going to go with the Mauser (Awful safety really hurt the Mosin.)