I have three that are my favorite sleds
1973 Viking Vigilante SS, 440 Kohler fan cooled, wide ski stance, short seat made for 1 person, foot stirrups, and a rail suspension. I ran about 2000 miles per year on that sled.
1980 Polaris Centurion, 500 cc liquid cooled 3 cylinder engine, it felt like the fastest sled I ever rode with its 32" ski stance and 6 inches of rear travel. I did my first backpack trip on that sled, almost 600 miles in two days
2012 Switchback Assault 800, a perfect sled for my type of riding, I can do 300 mile days and feel fine even if the trails aren't great