Well definitely Poser 2010 to Poser 2012 has many improvements. Even just the layout of 2012 is far better, especially with the ability to have a floating or non-floating window. Too many other things to list off the top of my head.

I started with Poser 4 then eventually went to Poser 5 (which I think was the first one to have these different rooms). That seemed like a jump at the time, but both of those now seem really primitive. Well, even Poser 8 seems rather primitive but acceptable.