I think that depends on what you want to model. I'm doing architectural models and started with Cinema4D but probably partly because of my strong (Auto)cad background I really struggled with c4d, although I hear it's much easier to learn than 3DSMax. Mainly because of Cinema4D's lack of 2D hidden line geometry export (to Autocad), I started in Rhino a little over a year ago and it has really grown on me. Since Rhino had its birth inside Autocad, if you know Acad then the learning curve for Rhino is probably the least of all the 3D modeling programs. I love the Rhino/Maxwell combo. However, there are what I consider some weaknesses in Rhino that Cinema4D addresses much better. As you may know, Rhino is a NURBS modeler and Cinema4D a polygon modeler. With Rhino, every NURBS object at export via the excellent plugin has to be translated to a polygon mesh for Maxwell to render. With C4D you're working directly with the polygon objects so the export via the also excellent Maxwell plugin (same person wrote both) is a little simpler, there is not a separate render mesh created for each object like there is for every NURBS object in Rhino. The other factor which comes into play with very large models/scenes is that C4D handles the same geometry with smaller file sizes. I've been working on a large model in Rhino and am starting to run into my 12gb RAM limit, so will likely have to export the architectural model to Cinema4D and add my landscaping there. Also, Cinema4D can be used either as a 32 or 64 bit app, but Rhino v4 is only 32 bit, however, Rhino v5 is both 32 and 64 bit but it's still a WIP, hence sometimes things are "broken" (FYI: I use the Rhino v5 wip on a daily basis). My suggestion is to try to narrow your choices down to 2 and download the demos and see if either seems to appeal to you more. I might add too that you should take a good look at Modo. They have a working demo you can play with. Frankly if I was looking for a polygon modeler now I would likely choose Modo over C4D...just seems like the modeling tools appeal to me a bit more than c4d modeling tools. By the way, one of the main reasons I ended up with Rhino is that I can take a Rhino model and export pretty clean editable 2D hidden line elevation, section, and roof geometry (dwg format) right into Autocad....this is "alternative" BIM

. After doing some research, that was the main reason I chose Rhino. You can not do this with a polygon modeler like Cinema4D. The only other 3D app that I'm aware of that can do that is FormZ. I do not know if Modo can export clean 2d hidden line geometry for use in 2d cad apps...I would check that out first....and if someone says it can, be sure to try it out for yourself.