Are you suggesting we change personalities instead of class and base the synergy on personality? If so, that's definitely a new, but potentially interesting direction ....
Back to the class stuff while we're on it, though .... I wonder if the way to go might not just be one generic Justice League Recruitment power that could be on both of Martian Manhunter 2.0 and Batman 3.0 (so you have flexibility with your hub) but that lists the following classes:
Champions, Officers, Scientists, Vigilantes, Archers, & Warriors
That'd get six of the big seven at least (poor Aquaman
) and I suppose we could throw in Kings there if we really wanted to.
The reason I'd be for not splitting up classes into different recruitment powers is that it'd be overly prescriptive on army builds: i.e. Martian Manhunter would work best with certain classes and they'd work best with each other, whereas Batman would work better with other sets of classes and they'd work best within their group. I'd worry it'd basically split the classes into Justice League West and Justice League East, so to speak, and overlap wouldn't be very encouraged.
I haven't looked at personalities enough to know whether they'd be easier or harder to group. Valiant does seem like a good choice if we go that way, though, but we'd have to check to see who already has that. Heroic could be a good unused personality if we want one that doesn't necessarily pull in any preexisting designs.
Edit:
I misread Sock's post. He's saying that you could call out the Valiant personality to change classes with. It's a thought, though it does lack a certain pleasing parallelism.