I don't think there's a real easy ranged class at the moment. Each has challenges unique to its setup that make things difficult. Perhaps it may boil down to you trying them all out, and seeing which "challenge" suits you best?

Example: I've tried all of them personally, and so far I enjoy the Bard the most with it's needs to keep an eye on procs and manage multiple oGCD's. I like BLM the least with it's need to manage casts with movement, SMN somewhere in the middle, and RDM is interesting but haven't gotten to it yet (I fall victim to the anti-uniformist bug as well).

I suggest try them all, and see which one stands out the most for you. Even RDM...you may end up liking it more then you would think! or not...but again, I don't see the decision being one made with just other peoples opinions on what's "challenging" or not, because at the end of the day, vanilla, chocolate, strawberry and rocky road are all different flavors, but they are all still ice cream.