I would have to go with moddable games since then you can add variance to them, even better if you can make your own mods. That said my list would look something like (in no particular order) Also, are full trilogies/series included? Cause that would change my list a bit.

1: WoW
2: League of Legends
3: Terraria
4: Legend of Zelda Link to the Past
5: Bladur's Gate II (or some other top down RPG)