I think you can get to top 10 with any kind of team as long as it's leveled/geared/starred up, so yea start focussing on an A-team of five. There's plenty of info on these forums on good synergies like AoE teams, high DPS teams or healer teams. You're in a luxury position with that kind of roster so just pick a team you like playing with and if it's maxed, you'll get back to top 10.
Here's my team I finish top 5 with every day and i'm nearly f2p (spent 10 bucks):
Sid 7* (leader), Lumi 7*, JC 6*, Old Daka 5*, Dooku 4*. I finish nearly every battle with all of them still standing thanks to all those heals and the occasional res. It's a bit boring to play though, so now I'm working towards an AoE team with Sid (Leader), Vader, IG88, Poe/Phasma and Lumi/Daka.
You've got a lot more options though so you could make even better teams. Your main issue right now is that you're spread too thin, so just focus on one team of five and you'll get there.