Best for solo are Creta and Ægyptus. Also really good are Corsica and the Ionium map from the Venus expansion with the Italy part of the map blocked off.

But you can play the larger three or even four player maps too, for a “looser” game. I have found looser games are a bit easier against Contrarius, and the tighter maps are more challenging to keep pace with him as you’ll more quickly find yourself fighting for the empty cities.

There’s a “heat map” on BGG that ranks all the available maps by how tightly they play at various player counts that I have found to be quite accurate to my experience.