If you want the easy road, Artlantis is the way to go. Cinema 4D offers more features than Artlantis, but Artlantis is easier to learn & use and runs super fast. You can do quick radiosity renderings using the Artlantis rendering engine (which, in many situations, may be all you'll ever need to do), plus in Artlantis you've also got the optional Maxwell Render engine inside, in case you ever need to do physically accurate renderings (slower, but worth the wait if it needs to look like a photograph). There's a 30-day demo version of Artlantis available at artlantis.com, which also includes a 30-day demo of the Maxwell Render engine plug-in.
I can't say about Cinema 4D, becouce I've never used this software.
Artlantis is fast but getting high-end renders was quite a struggle for me,
although I've seen people do it. I failed :)
You can also check out maxwell render.