I don't think any job is overpowered, I believe some are just naturally more annoying than others.
As SMN, I really do not see what everyone's talking about how hard it is to kill SCH. If you kill Eos, possibly twice due to SC, then the SCH is cake. I think WHM are waaaay harder to kill.
Some dude mentioned that melee can kill anyone 1v1...Healers are top dogs at one on one so it's not even worth the time to fight them, although personally as SMN I feel fairly confident fighting SCHs.
Also did everyone suddenly forgot that SCHs main source of damage is pretty void when it comes to fighting a whm.. Esuna > DoTs. Even Regen > DoTs. I think WHM vs SCH is like the FFXI equivalent of RDM vs RDM in where the match could go on for days without a victor.
The most annoying job for me as a SMN main is BRD hands down. It's not to say I can't slay them 1v1 cuz I always do, but in group battles when I'm tryna kill the SCH but can't cast cuz of the BRD spamming me, it gets pretty annoying.