Dragoons have a lot of skills and they do a lot of Off Global Cooldown skill weaving (using skills that have no global cooldown between skills that do), so in that regard, it might not be for you.

Monks have a few skills less, but to maximize your damage you need to constantly move back and forth to hit the target on their flanks and on their back, and dropping that Greased Lightning makes any decent Monk die a little inside.

Ninjas have about the same amount of skills as Monks, but they have Mudras to deal with, which can be very frustrating if your latency is anything above 80ms, but on the plus side you don't need to worry about positionals (yet).

As for casters, I agree with what Zephyr said about Summoners, and I don't have much experience on Black Mages.