Just get both. You can easily get an Enfield No. 4 for $200, and a Mosin Nagant will only add around 70-90$ to that price. The Mk III's are pricier and heavier and come with military sights; you'll probably achieve greater accuracy with the No. 4's aperture sights regardless of the capabilities of the weapon. We can assume that either one will be expected to shoot 2-3MOA - there are of course diamonds in the rough, but accuracy with any milsurp is hit-or-miss. I've never loaded an Enfield with chargers, but I can tell you that the Mosin's are a PITA to load quickly under duress. Surplus .303 practically doesn't exist anymore. Modern production is cheaper, but nothing beats Eastern Bloc corrosive surplus that you can buy 20 rounds for 6$ with.
As for ease of use, anyone will tell you that the Enfield's bolt is slick and fast. The Mosin's is considerably clunkier, and the chamber must be heavily cleaned of Cosmoline before you can attain smooth reliable functionality. The short bolt handles allows little leverage in operation. Historical value tends to fall towards the Enfield, but a lot of No. 4's were manufactured post-WWII
The Mosin is often underrated in terms of historical value just because of the fact that there's so damn many of them, but it's food for thought that at one point or another, they've been pointed at the armies of nearly every country in the West (Ukraine, Japan, Lithuania, Poland, Germany, Finland, Austria, Hungary, America, Britain, Estonia, Latvia, Turkey, France, Romania, Czechoslovakia, Mongolia, Greece, Italy, Bulgaria, Georgia, and most importantly, Russia). They've seen the brunt of both World Wars and most of everything in between, and I feel that an early production Mosin has as much claim to history as any other rifle.
Personally I'd suggest getting a Mauser 98 variant, though. I'm a sucker for its rimless rounds.