I've used both (the Macintosh versions of each). I find Cinema 4D to be easier to use. RDS is showing its age: its different modellers were designed as add-ons to the program and only later bundled in and made to look like a completed whole. I've always found it very cumbersome that the Free Form Modeller is a separate "mode" from the regular modeller, and the Mesh modeller feels like an entirely different program. Cinema 4D is much more consistent in its interface. The downside of Cinema4D is that it isn't from Metacreations: being from the same company means that RDS and Poser tend to interoperate reasonably well. An OBJ file exported from RDS has a good chance of opening up and looking like you expect in Poser. In cases where things don't work, it is generally a "well known" problem for which you can find tutorials explaining how thge fix. Cinema4D on the other hand sometimes does things differently. C4D will create polygons with normals pointing the "wrong" direction for Poser, resulting in models that appear inside out when working in Poser. You can search for Cinema 4D in the Forum to dig up some of my previous posts on the subject. I've always been able to correct the models, it just requires several "Cinema export -> load into Poser -> what on earth is that? -> back to Cinema 4D -> tweak, tweak, tweak -> Cinema export" cycles. Despite the occasional wierdness bringing things into Poser I find myself using Cinema4D for most modelling tasks now. If you use a Macintosh, recently there was a demo version of Cinema4D GO in a computer graphics magazine CD REPLACE. Maxon offers a special upgrade price of $50 to get the full version from the demo. At $50, Cinema definately rates a "buy" recommendation. I paid the full $199 a while back, and am still happy with it. You should search the Forum for Cinema Demo to check into it.