Akbar is your best lead there, unless you gear up Wedge. The speed from ackbar is great, and very useful to call assists with non attacking abilities.
Solo is super important, you'll want to use him for a long time, along with C3P0.You're lineup is fine, given your gear levels. I'd gear up that R2 and use him. He's pretty vital, both for Rebels and Resistance lineups.
Commander Luke is unlocked by having 7* of the following: R2D2, Obi-Wan Kenobi (Old Ben), Princess Leia, Luke Skywalker (Farmboy), and Stormtrooper Han. Then you need to wait for an event that happens every 2-3 months (similar to how you got R2).
As for a second team, your best bet would be Jyn lead, with Chirrut, Cassian, Baze, and K2SO. Given you don't have all those, you can mix and match as you can.
As for your first team, the ideal lineup would be something like CLS, Han, Chewy, C3P0, and R2.
Once you have Wedge geared, he can replace Ackbar lead and team up with Biggs with your remaining rebels.
Always keep the Phoenix squad together though!
(Again note that your current lineup is fine, I list the other teams for your future Rebel plans... there are loadsssss of rebels).
