Long time Repetier Host user here. but I use an older version (v1.0.6) as one of the updates caused major issues with my printers. I prefer Slic3r for slicing my models to print
I have S3D, and to be perfectly honest, I do not like it. But I am forced to use it with my Beta Testing Machine (manufacturer insists). Yes, it has lots and lots of settings, but the ones that matter to me do not work the same way they do in Slic3r - in fact, they will completely screw things up if I try to adjust them in the same manner as I do with Slic3r.
I know there are a lot of people that just love S3D, but I am not one of them.