I upgraded from Carrara 3 and I really like version 5.  Actually I used Poser 6 to get the wonderful DAZ bundle with TransPoser.  The interface is a big improvement and it has a lot of new features.  I skipped version 2 and 4 because I found myself using Carrara 1 and 3 less and less.

I'm glad DAZ bought it and offered such a wonderful deal otherwise I would have passed on it.  Hexagon 2 was also worth getting especially for 1.99.  My all-time favorite "was" Vue 5, but it crashes so much when importing Poser characters that I doubt I'll upgrade to version 6.  Carrara 5 imports without a hitch and the renderer is so much faster.  If Bryce would have more realistic vegetation, I'd go back to it.  Carrara 5 is a pleasant alternative.

Poser 2, 3, 4, 5, 6, 7, 8, 9, 10, Pro 2014, 11, 11 Pro