Now we have rarities assigned to pretty much everything else, but not really characters. I think it would be helpful in determining where characters should end up on the board with the release cadence.
I compare this game to magic a lot because that's what it most resembles to me. A turn based strategy game. They have a card rating system that goes: common, uncommon, rare, mythic rare; and I believe it would work perfectly for the characters that you have.
Common: obtained from Galactic War store, or Cantina nodes,
Uncommon: obtained from Squad Arena store, Cantina store or multiple hard nodes
Rare: obtained from guild store, achievements, or fleet arena store
mythic rare: obtained from legendary events, raids, TB special missions, a single hard node
Now the way the way that MTG does it, the higher the rarity, the stronger the card will be. Bearing everything above when looking at the way the character release cadence is shows that in general, EA/CG has done an excellent job of placing the new characters on the board.
What I would really like to see, however, is a shuffling of the older characters' placements. Lobot, for instance, is nowhere near good enough to warrant hard node only placement. He should be in galactic war or have a cantina node. Ugnaught and CUP shouldn't be in squad arena. They should be in Galactic War or on a Cantina Node as well. Jedi Knight guardian and Mob Enforcer should also be in that lower tier.
Gamorrean Guard, Zam Wessell, and Tusken Shaman should be in Squad or Cantina stores instead of guild and fleet.
There are some characters that are honestly too easy to obtain compared to their relative worth and deserve to be moved up the ladder as well. Captain Phasma and First Order Officer should trade places.
Basically, I'd like to see
difficulty to acquire = effectiveness of the character
and, while you are **** a good job of that with your current releases, there are a dozen or so older characters that really need to be relocated to make that the case in general.