While I think foph have the best regular tech casting of the 3 mostly because of short charge, it seems to me they also have the worst compounds because of lower multipliers. For light/dark and comps multipliers alone, Te subs should have 1.58 ish for non weakness, and 1.73 ish for weakness, along with 90+ base t-atk compared to phantom if you take the technique ups from the Te tree. Phantom sub on the other hand will have around 1.56 assuming you crit 100% of the time so their short charge is what makes them shine.
Foet is 1.67 ish always, which means the comparison of light and dark being better/worse depends on weakness. Compounds on the other hand seem close since weakhit only triggers for the specific element of that hit, so unless the enemy is weak against both elements, weakness will trigger for about half of the hits. Good multipliers but without pp management skill, the main appeal is damage balancer imo.
This is from tree alone though and no SSA, so phantom higher crit rate may close the gap for comps. There is also the fact that both foet and foph will have better fire elec and ice, so thats a plus for them too.