by Hannibal Rex
There's not much to upgrading orbitals; Primarily, you want to make sure they're strong enough to face single enemy interceptors on their own. Against anything bigger, they're merely speedbumps due to pinning, or they're support for your fleet.The Ion Turret is great for its power cost. I'd keep it under nearly all circumstances.
That leaves two slots, with barely any room to get creative. Computer (Positron, Gluon, Sentient Hull) + hull (Improved, Shard, Conifold Field, Sentient Hull) is what you want.
I suppose it's also possible to use 1 computer and 2 missiles.
If your opponent uses (only) Anti-Matter Cannons, investing in hull isn't worth it, unless it's the Shard Hull or Conifold Field. You can replace it with something more offensive; either a second computer, or another gun.
Keep in mind that you can repopulate the orbital if it gets taken out, as long as you win the combat. If it's enough of a threat that your opponent targets it instead of destroying one of your ships, it has served its purpose.