Jokes aside, imo, Skyrim, Starbound and Final Fantasy XII are great games to sink a long time. Of those, Skyrim I played the least due to life happening, but was enough to sink a few dozen hours already. Starbound easily surpassed the 600 hours for me, even if I barely use mods or played multiplayer. And Final Fantasy XII, on my first save I got to the final boss, I was nearing 300 hours already, and for a game originally on a 4.7 GB disc, it has a lot to do, so much so that, in that save, I was just starting to scratch past the surface.
I'd argue FF12's content is primarily grinding, though. I liked the game, actually just beat it this summer. But, I was definitely ready to be done with it by the time the credits rolled. I finished with around 70 hours, I think. There are a lot of secrets and whatnot, I just wish their crafting/bazaar system wasn't so tedious with its requirements.