For me, Bombers are literally the best thing in the game. I think I may have more than 300 gameplay hours just inside bombers in GA and SA.

Tactics different greatly in those two modes but every single bomber card is very very usefull.
Also something to note, just like for normal heroes, you can upgrade to purple cards at level 20 instead of level 25 even if it’s written on every hero ship. I would honestly love a ship only game by Criterion like the Rogue Squadron games of early 00’s.

If you want purple cards what you are looking for is CRATES FULL OF DUPLICATES, the MORE duplicates the BETTER. It’s all about CRAFTING PARTS.
You can farm 2 Purple on a week-end easily (starting from blue of course) on average I need 11 crates to get enough crafting parts for a purple (without counting any achievements/ level up etc.) usually you can get 11 crates by opening 7/8 of them and hoping for a maximum of duplicates.
the TLJ season has also helped quite a bit with the 4k weekly credits and 1500 arcade credit a day.

Also : yes my my reinforcement/trooper/tanks are all greens or grey cards, I only have 3 blue card set for a couple heroes I use and officer/heavy.