The Federation. I think they have greater numbers, transporter technology, and interstellar allies with advanced weapons and cloaking devices. As long as it isn't Original Series or Enterprise when they don't have those numbers or allies.
The Vidiens who come in afterward and harvest the best leftover bodyparts from everyone.
Given the sheer number of ships that Starfleet cold amass, let alone obvious technological superiority, the Brown Coats should have asked for help, then backed out of joining the Federation; there would have likely been no reprisal.
Nerdy enough for you?
Federation had FTL and Phasers
Federation, they are god like in there technological lead, it would not even be a fight