My favorites are the old Russian Model 91 and it's offspring. It is not a fine gun or a rare gun, but it offers collecting possibilites to a guy who works for a living. The ammo is cheap enough to shoot, and they function well. No matter how many you collect there is always one more or a better example of one you have. For the cost of one rare or semi-rare firearm you can have a room full of these historical rifles.
It is also, cool for me, who as a school kid in the 1950s and 60s, did the duck and cover drills, to end up with the Russians toys. I own the guns that protected Kruschev...... bury me, my a$$!