Also depends whether you're willing to buy from C store for your account or via emblems for a specific character.

Fleet escort - max tac with a slight emphasis on engineering (lt and ens and 3 eng console slots).

Advanced escort - max tac with a slight emphasis on science (lt and ens and 3 science console slots)

Defiant retrofit - get a cloak but your eng/sci ensign slot becomes a tactical and you lose your 3rd engineerin/science slot.

MVAM advanced escort - gives you the mvam console (can be used on the original adv escort too). The only difference is you get 1 ltc science boff and a ens and lt tac (3 sci for 3 tac abilities). You get a slightly stronger science ltc ability like TSS3 instead of a tac ability like BO3.