[Twan]

In nation mods, my favorite for games with vanilla nations too are Zepath's ones.

For modded nations against modded nations, try warhammer ones, or Amos mods (balanced against his other nations only).

And avoid mine (Greyhawk mod was a too big project, and current version is a mess with lots of unbalances, unfinished national pretenders and some id conflicts I can't find the courage to fix).