Both are good choices. You won't be disappointed no matter which one you go to.
Jiko has the advantage of a great resort to walk around and look at - as well as looking at the animals on the savannah. Of course, for Citrico's you get to walk around the GF for a bit and that's nice too.
Citrico's is an elegant room, with a very upscale feeling. If you're done eating early, you might walk down to the dock area and catch Wishes or the Electric Water Pageant.