Personally I always recruit
Mercedes- she is the best healer in the game
Ashe- Ashe is a awesome sniper, bow knight, and wyvern rider when I played him. Plus he is best boy so I always recruit him.
felix- so strong with his ability to us his fists and he can have a sword too. I actually made him a mortal savant in one run.
Ingrid- she has saved my ass so many times as a falcon knight to the point where her nickname is savior
Lysithea- omg she is an amazing magic user and making her a Gremory makes her even better
Hilda (if possible on run)- she is a savage on the battle field make her a warrior or a wyvern rider and the enemy is in trouble.
Shamir- awesome sniper and hunters volly is awesome for her to have(plus she does not have a relic that will need to be fixed like a certain blond haired warrior)
honorable mentions are Caspar, Petra, Bernadetta, And Seteth