It pretty much boils down to a bolt action versus semi-auto. If it was only one, I would go for the Yugoslavian SKS. I paid $149.95 from AIM for my last one (Damn that C&R License) and it's a beauty. Be prepared to spend a LOT of time removing the cosmoline from any of the Military Surplus rifles except for the Mosin-Nagant's, they have heavy oil, but no cosmoline. Let us know what you get and I'll steer you to some C&R sites.
Depends on the action and ammo availability. If I had it to do over again, I'd choose the Enfield No. 4 MK1. Surplus ammo is iffy and can be expensive but I reload so its not so much of a problem. The SKS is a neat little semi-rifle and ammo is dirt cheap (I have a Yugo SKS). The Nagant is a cool bolt rifle and ammo is relatively cheap but that thing does KICK (mine is the Mod 1938 w/o bayonet).
What do you want the rifle for? Collector, shtf or general shooting/hunting? All three are excellent but it depends on what your plans are.