Honestly, useful crew members.
So far, there are some that just exist for their sex scenes
Give them something special, because without it, they just end up being dumped for ones with special benefits, especially now since Crew real estate is scaled with Ship Upgrades
Like you have characters like Reaha that have so much written for them, yet I'm inclined to remove her in favor of Ramis for whomst I could literally not care about aside from stat training
You have Kiro, who is known to have deep connections in the underground, and has gotten around a lot, yet I'm inclined to keep Anno who is interesting, but really because she gives the best rates
You have Bess/Ben, an advanced sex robot that could probably give you a passive boost in willpower for finishing all his/her events, but nope, have Yammi, a fish girl grown in a tube with about as much going on with her, but hey, buff
With the ship change that actually made choosing your crew a thing, we should also see reasons to keep crew-members, but honestly, that just seems rushed.
More than half the available crew members are worthless, especially as combat encounters get harder and harder
Like if not at the moment, at least plan out some sidequests to make them useful, make Reaha give stat boosting milk like the cowgirl bar in Dhaal
Make Kiro train you in not-nutting so that you get a higher maximum lust as long as you train with her like you do with Paige
Heck, make Bess/Ben give loving hugs that boost willpower
Just something to make them useful.