I find that the 1960s Chinese ball surplus is the most accurate out of a Mosin-Nagant. TradeEx might still have it. Good smell for surplus powder as well (as weird as that sounds). I've had problems with this stuff in an SVT-40 though.
The least accurate for me has been the newer Canada Ammo Chinese surplus (Machine gun ammo from 2011).
The Bulgarian and Russian stuff is good too, can't really go wrong.