Race advice for new mega-game

[Endoperez]

There's no "best" nation. If there was, it'd be what you described first. For the latter, read Baalz's guide to Marverni. His guide makes it seem overpowered; the Druids are good combat mages (astral and earth), they also have good researchers and their endgame teleport squads are good.

[Aezeal]

Marveni? Didn't expect that one to show up here.

I must admit the druids seem nice,
but are the Marveni researchers considered good?

The sacred troops seem so overpriced though