What rpg system would you use for a 60+ session fantasy campaign?

[GrimCo]

Yep. The engine or game style I would want for a 1-2 shot, a game of a dozen sessions, a game of 60ish sessions, and a functionally unlimited one (at least 100+ sessions) would all be very different.

Same. System needs to be flexible enough to accommodate and mechanically support at least 3-4 game themes and genres so i can throw some variety of scenarios. 60+ sessions, by frequency of my group playing, is 3-4 years in real life. That's long time to keep someones attention and enjoyment.