You're going to be splashing out a lot of cash so this kind of decision is not one to be taken lightly. What I would suggest is that you download the evaluation version of each piece of software and spend some time with them and see which suits you best. Not all software appeals to everyone in the same way.
Cinema 4D can be got from
http://www.maxon.net/index_e.html
Lightwave can be got from
http://www.newtek.com
I have to say when I was making my purchasing decision, I quite liked Cinema 4D, I could make it do things and get some nice renders up pretty quickly. I fell in love with Lightwave mainly because of the modelling tools and the price.