I think saying X job is easier than Y job is a bit funny in any MMO. Especially one that caters for controllers with their limited keys.

I've played a few classes, I enjoy RDM best, because I enjoy it. I loved DNC for a while, but I got bored, same with Samurai, Ninja, Dragoon, Summoner, Black Mage.

There is no "easiest" or "hardest" it just depends if you click with the job, doesn't mean countless others will like or hate it, struggle with it or find it simple.

Play what you like, what you enjoy.