I'd honestly say play what you want. Only at the absolute bleeding edge of level where they speedkill for fun is where meta applies. It may help DPS checks at the layman level but a better player on a non meta role is better than a shitter on a meta one.

To answer your question, NIN has never not been meta, and I don't see that changing. The day it does, the servers are gonna go offline. BRD has similarly been super useful, and is currently meta. DRG basically can tag along because of BRD (it has its own merits, but without this it would be meh). MNK/MCH and maybe at a stretch SAM compete for the last slot. MCH obviously works well with DRG and has the highest utility boost out of them all. MNK is very powerful with a bit of utility and SAM is super powerful, but we don't know if that is enough yet.