from a pragmatic point of view-

aedui have carnute cingetos (druid chant, inspire nearby units)

arvenerni have arjos (armoured spear unit)

these are both after the reforms. cingetos can only be recruited in 1 place while arjos has several recruitment places. cingetos are better imo because there are already plenty of other units that are similar to the arjos.

however, unless youre roleplaying some sort of snail-like progress game youll probably never reach the required reforms to make these units, or your borders will be so far from home that it would take too long to send them to the front.