What about for stat boosting on girls that are whaleship filler? Any preference?

When it comes to whale: I would advise always go with the higher TP equips unless the stats difference is minor. This essentially means attack-based gear should be prioritized. Fillers should go more towards defense, while deck units should focus more on the attack side of things. It has been my experience that a small increase in defense can make a big difference in survivability.

When it comes to units: You really need to think about the unit itself. With that said, if it is a debuffing team, you want to front-load as much defense as you can. Only once you can surivive what I would consider 8-12 hits without healing would I focus then on the attack side of things.