My ideal Rebirth YJ team would be:
Red Robin - once he gets back, he should lead this team again.
Scion (Kon) - clone of Superman and Lex Luthor
Wonder Girl/Fury (Cassie) - WW's niece, she'd finally start acting like a real hero again.
Impulse (Bart) - would get a retcon throught time travel and be his old self again.
Ms. Martian - she should be back ASAP.
Bunker - sort of the team's GL in terms of powers, but his own character. He works well with the YJ4.
Aqualad - he belongs here, instead of with the TT.
Speedy (Emiko) - she'd be the youngest member, sort of the team's Damian.
+ Red Tornado, acting as a liaison to the Justice League.
Blue Beetle and Power Girl could also join down the line.
Unlike the Teen Titans, who should act independently, this team would be created by the League with the express purpose of training heroes capable of replacing them should they retire or die.
To further differentiate both teams, I'd avoid too many legacy heroes in Teen Titans. So no Aqualad or Emiko there. Only Kid Flash and Robin (because they'd be redundant in the YJ anyway).