I like the Rebels because they're the good guys, and they're the underdogs.

I've had all 3 as favorites from time to time. I started out playing Rebels and I was too happy with the game mechanics to be bothered by how awful I was at flying them! Or list-building with them. Never felt like I could build a squad that I could fly competently.

Eventually I tried Scum and fell in love with their alternately janky and OP weirdness. I never managed to git gud with them (and I can't fly half their ships for crap) but I loves me my G1As and Feedback Z95s.

More recently I've been flying and loving Imps. Krassis is ridiculously fun to fly anytime, and I've slowly gotten not-terrible at blocking with Academies or Epsilon FOs. Gotta love the FO!

1st : Scum - for their diversity.

2nd : Rebel - for the 'good guys' nostalgia.

3rd : Empire - for their stark uniformity.