My favorite MLP:FiM Pairings.
FlutterMac - (Fluttershy & Big Macintosh) Though highly fanon, I think it could work. I seem to be rather fascinated by the idea of The Shy One pairing up with The Strong, Silent Type. They say "Silence is Golden" and this could be one of the best pairings because of that.
SoaringDash - (Soaring of The Wonderbolts & Rainbow Dash) To some, it may seem kind of obvious to pair Rainbow Dash up with someone from The Wonderbolts because of how much she loves them, but when you check out all the pairings, you realize most people see Rainbow Dash as a lesbian and the so called "evidence" of it all is just laughable to me. This is what makes the obvious choice so perfect to me. It's the kind of thing Rainbow Dash would do just to rub it in everyone's face and disprove them all. Plus, I could actually see it happening in the show. I seriously could.
As for the other 4 mares, there's just not enough love interests around to make a decision. For now, it's OCs for the rest.