if you play STF's putting anything into shields is a waste
my STF build so far looks like this:
eng sci -> emergency to shields (the only shield buff i use, it's not much use vs. Borg anyway, but it's enough to get them shields back up over time, after the battle or while the cube is targeting someone else etc. Hull heals and buffs are much more important... i even see myself healing beat up cruisers every now and then)
universal 1 -> SCI polarize hull (vs. tractorbeam, and general damage resistance) + hazard emitters (neither use actual SCI skills or consoles to buff these, either that or another engineer)
universal 2 -> ENG eng team + aux to SIF
the 2 TAC's depend on if you want to use beams or cannons and are pretty much the usual, not worth mentioning here.
as an engineer i guess you will run into problems getting your hands on Attack Pattern Omega 3 or Beam Overload 3, that means either letting another player train your BOffs and maybe getting robbed, or buying them on the exchange for a bazillion EC
Engines Min (or just enough to get the most out of Bonus Defense)
Aux all what is left
all the Hull heals use AUX Power, as i said Shields are no use vs. Borg, so no use putting energy in there either.