For the Thrawn event, you want to be doing as much dmg as possible. Ezra being #1 obviously, Hera can easily be the 2nd biggest dmg dealer, even bigger than Zeb since she can expose. Chopper's basic does not help in the Thrawn event. You want Kanan's unique maxed and Chopper's unique maxed. Everyone else can have 7s for the rest of their abilities.
Idk why you're listing other omegas outside of Phoenix here. This is about the Thrawn event. Chopper's basic gives 10% extra chance. So 50 to 60% chance. Not worth it. I'll take the extra 15% extra dmg that Hera can put out during the event.