Slitherine

Which nations for a 4-6 player MP game who:
- are not one of the big ones
- roughly equal in power
- interesting to play

Difficult question with a lot of 'depends' but I still would like to know your opinion.

We just more or less finished a MP game were we had a Macedonian runaway. I would prefer nations that do not easyly snowball.

Aethiopia is an interesting pick. No slouch by any means; you can easily assemble 100 combat power and a decent stack if you expand quickly and play your cards right, but it's definitely not one of the heavy hitters, and is vulnerable to being blocked in by Saba and Ptolemaic Egypt.

+1 for Aethopia
I find Pontus to be a good choice for this as well. It has unique mechanics and is interesting to play, while not being really a major power
One of the Greek minors bordering Macedon, Kolchis or even Massalia might be good picks too, especially when the DLC will come out and allow Colonies and Trade posts

If you draw a line north-south along Italy, you can easily find west of that line 6 roughly equivalent nations in modern day France, England, Germany and Spain. All close enough to interact with each other and only big power threats are Rome and Carthage. Neither Rome or Carthage are big threats early on. Could make a pretty good game especially if you don't allow human nations to ally with each other for the first 50 years or so. Also play on experienced to slow down any blitzkriegers.