Don't focus so much on criticism, a lot of players are veterans and are just ticked off with a lot of changes. Likewise balance patches will come and go (and that's a whole discussion for another thread). That being said, all of them seem middle of the pack right now with Sam being higher, although still too soon to really tell. What won't change is the playstyle however:
Monks and Dragoons will focus a lot on positions. Ninjas are a bit more timing focused. Monk is fast, ninja is kind of fast, dragoon hits slow and hard. Utility wise puts Nin/Drg higher, but Mnk has some new raid utilities.
Best suggestion is to run Palace of the Dead with each class and see what feels more fluid and fun for you, you may like the faster playstyle of mnk to drg for instance.