At least with Epeiros you will have developed more substantially when you do take on the Arche. With Pontos you will be scraping for Sinope, Nikaia and Byzantion - and hope the 4 of them combined make you enough money.With Epeiros the Arche will be a tad less frustrating.

Recruitment could be a serious issue, especially on Huge - your cities may run out of citizens if you are not careful.

Would you be using a money script, to reduce the out of control income of the AI factions? If so Pontos may well survive.