Droids are still better than a full Nightsister squad with both of their Zetas.... So you can't say that Zetas are the problem here.
Droids have no depth, and I'll agree Droids are kinda getting shafted right now with Chopper being released and not another droid that isn't actually a rebel and not really a droid.
I'd like to see Droids get more synergy past the "We all crit and we crit hard and we get lots of TM cuz we crit. Oh and did I mention every droid can crit a lot? Cuz they can." That's not really synergy, all the droids just do the same thing. Except for B2 and GG (Don't count K2SO and Chopper cuz they're obviously rebels). B2 is universally great, and GG has so much potential but just doesn't quite have enough going for him. Droids need more support characters, support characters really fill out squads, but right now they just have a ton of attackers where HK is the only droid support. Sure Poggle is a support character, but he's gonna get more separatist synergy than direct droid synergy (at least he should), there needs to be a droid that is actually a support character that doesn't necessarily need to be in the leader spot, OR a new leader that can allow the droids to do more than one thing. Zeta's just expand on what teams are good at, but droids are already basically perfect at crits so theres really nowhere to go from there, and they'd have to add something entirely new to them and it just wouldn't make sense because that's the one thing they actually do. They don't do anything else. Droids need more depth of playstyle, but the problem with that is that everyone likes to play droids because they're fun because all they do is crit and that's fun. Theres your problem, your team with no depth is fun, but because it has no depth you get beaten unless you get solid RNG. If you want depth it's gonna have to do more than just 1 thing, and you might have to play them differently, and I honestly feel like being force to used droids differently might make them less fun to use...