For personal powers I dont really use them much since they dont seem to add much. Security Escort is probably the most useful for that last hard mob you have to face.
I just wish they would STAY with you for a longer period of time because more than a few times these guys just beam away if you even duck behind cover for too long.
As for Bridge Ofifcer powers:
I run with 2 tacticals, 1 Engineer and 1 science. Recently I have been buy Very Rare officers off the exchange with the traits I want.
Namely: Betazoids because apparantly they get a natural ability to enhance expose chance duration, team regeneration and have lower threat generation.
Thus, if the trait works like it indicates a full team of Betazoids equipped with expose weapons should be lighting up groups of enemies so I can just pop my split beam weapon and vaporise them en masse.
I originally ran with some Klingons but the tribble screaching quickly got annoying for me. Yes, I give my officers my special tribbles like the damage buffs. As such 3 rare klingons only result in massive amounts of screaming from the tribbles.
That said, Klingons are walking tanks, they have natural threat generation plus enhanced damage with energy weapons and melee. Giving the security guy Draw Fire I pretty much made every mob go after the Klingon while the rest of my Klingons were malling them with flank attacks.
Unforutnatly, I just do not like running with a complete Klingon crew and I cant exactly put them in TOS miniskirts when they finally get implemented.
The best ground powers for your away team I have found are:
Draw fire - Tactical - put high resist armor on this officer and he can take the beating while the rest of the team take out the soldiers.
Target Optics I - Tactical - Chance to expose the target plus it increases critical chance and damage
Photon Grenade III - Tactical - Great for crowd control and the knock back is quite decent
Overwatch II - Tactical - It gives a chance to expose, I would prefer level III but naturally the skill is unavailable
Supression Fire - Tactical - Slows the enemy and debuffs their damage which is fairly decent for officers equiped with auto assualt weapons. If they do their spray attack you just slowed and debuffed the entire mob while you can lob grenades at them.
Stun Grenade - Tactical - I dont have my officers trained with this but I have it on my Grenade satchel kit and it claims to stun the target, it does seem to result in some exposes so it might be a good option to give your officers for that extra hold+expose chance.
That said, it only comes in at commander level and the skill required to get MK III is a captain skill. At that rank its not worth training for the bonus it provides.