I use Deck Crew and ITU on Legion. If I do not make fighters good on Legion, then I might as well pass on the ship and grab an Onslaught instead (for more guns and flux). If I use Legion, then I want to be good at both guns and fighters, which it can do. Likewise, if I cannot afford guns on Legion, then pass and grab an Astral instead.
Legion14, I use at times because it is the only ship that is built to use Hammer Barrage or Cyclone Reapers properly. None of the other ships with large missile mounts are suitable platforms for Hammer Barrage, not even Gryphon. As such, I consider Legion14 a torpedo boat (because flinging Hammers is the only reason I why bother using Legion14 in the first place).
Odyssey that focuses on guns does not need fighters. It is too busy zipping around the map and blasting enemies like a pure warship. I pick pods, Xyphos, Longbows, and/or Daggers for fighters, and keep them close to the ship like Gradius options. I do not bother with Deck Crew. It needs all the OP it can get to support guns, and with its limited budget, I often leave more than half of the mounts empty, one of which is the large synergy.
Recovery Shuttles... Crew are expendable, but OP is not, and ships are OP starved to an extent. Enough said.