If you feel like you know your way around the game well enough, I'd suggest turning off most of the options that get you attacked (golems/spirecraft hard, hybrids, FS) and doing a basic 80-planet 7/7. That's sort of the default game that things are balanced around and it's a good place to start. Or 7/6 if you're less confident, but I imagine if you can deal with exoes on 6/6 plain 7/7 should be fine.
I'm not quite sure what the differences are, by the way, but the developers say that at 7 the AI stops making intentional mistakes and plays as well as it can.