All around best Sub for MNKFollow

I chose Warrior, primarily because several of the traits and abilities it gives as a Subjob make it great for offensive purposes. Berserk and Aggressor offer large boosts to Attack and Accuracy (at the cost of Evasion and Defense, but with Monk's counter rate and their HP, that's not a huge concern) to help during TP phases and weaponskills. There is also the Double Attack trait which boosts WS damage as well as increases the rate you gain TP, Provoke as a means to start off a fight with a nice bit of enmity, since in most situations nowadays Monk does a fair bit of tanking nowadays, and lastly offers one of the highest boosts to Str, Vit, and HP (there are others that offer comparable, but they in turn lack some of the things that /War gives.

What Vlor said.

Dancer has some utility. Particularly for Abyssea parties where survivability is compromised by a lack of White Magic in the alliance.

For all other things, Warrior is the way forward.