--BOFFs--
The only places on ground that you can take bridge officers are episode missions, New Romulus, Kobali, and the Voth BZ. For the hardest ground content, they're not even present.
Boffs on ground are like incompetent versions of you. They spend time running around instead of shooting, they lay down mines and turrets and generators in far from ideal locations, and they don't any of the basic mechanics of ground combat like expose/exploit and flanking. So I wouldn't spend much on their gear since they aren't going to use it well. Give them stuff that you aren't using, mission rewards, or cheap mkXII blue or purple gear from the exchange.
But boffs aren't terrible at everything. Here are some things that they can do for you that might be useful.
1. Healing. Boffs can heal better than you can because the mechanics of healing others (stop firing, choose the ally, get close to them, cast the heal, start combat again) are cumbersome, but boffs are addicted to just spamming whatever skills you give them and they do it quickly. Vascular Regenerator, Medical Tricorder, and Nanite Health Monitor are all useful skills for boffs.
2. Spamming debuffs. Tricorder Scan (lowers enemy damage resistance, which greatly increases the damage of anyone shooting them) is always useful since you're always trying to shoot the enemies.
3. Spamming other stuff. Quantum Mortar is useful here because they have a long range and don't require a line of sight, but if you don't care about where stuff gets placed, then you can trust your boffs to lay it down as soon as combat starts.
4. Tank. I have a boff in a red TOS uniform with Draw Fire who is always the first to die wherever I take him.