Tough to rank I like all my classic sterns (Sans split second)
My favorite ruleset is Big Game but not a huge fan of the stacked flippers so QS wins top spot for me as it is in your face, simple yet challenging, cool bonus meltdown effect, great placement of drop targets. QS also has a home rom which resets bonus X after every ball which helps balance the rules a bit.
Quicksilver
Big Game
Gazer
Seawitch
Cheetah (W/ home rom)
Catacomb
Cheetah (W/ factory rom)
Freefall