I cant get a good straight answer for this but in terms of pvp what is the best first order team for both offense and defense. no slkr ofc and im willing to bet theres no 1 answer also edit i am only level 75 so i dont have zetas atm if that makes a difference in answer.
Once zetas become part of your arsenal, things become a bit more flexible. Phasma with her omicron becomes quite the inspirational leader in TW. Shouldn't necessarily be your first FO zeta, (zeta needed for omi), but worth doing at some point.
Hux's unique is important to zeta against certain team comps.
FO trooper has better damage than KRU and surprisingly better taunt durations if you use foo's marching orders, devious scheme on hux, and pinning shot on FOO you can reset his cd to taunt a ton (plus defense up and advantage).
The paramount thing to consider is debuff and buff removal. Certain teams dispense a lot of debuffs and buffs that can punish your team making ST, FOX, and Hux really helpful.
I use for debuff team: UKR (lead), SFP, ST, KR, Phasma (replace with slkr later)
non-debuff team: Hux (lead), FOTFP (omi is real nice but should be zeta-d later), FOST, FOX, ST (more valuable on other team so replace with phasma after getting slkr)
note: I usually just use my highest geared people for SA.
Before 85 save crystals for Finalizer then farm Hux and ST because it will take a while.