I've played a lot of incremental games and Realm Grinder I like the most. Right up there with the Paperclip maximizer game. The game has two prestige systems - abdicate to gain gems, reincarnate once you have enough gems to gain other perks. New mechanics are unlocked at different reincarnations and require you to periodically re-think your entire "grinding"...
pretty good
Only idle game that's kept me interested without feeling addicted
Will have to play more to know if its the greatest game of all time but would recommend!
doesn't count offline gains, which completely nullifies some playstyles/builds