Buy the latest Win platform if you are buying a new computer for personal use (business users may be tied into a particular platform). If you don't like Win8 (like I didn't at first) then install Classic Shell and it will feel like Win7 BUT you can play with Win8 at your leisure and when you are comfortable, switch over (or not).
When you go looking for a new car you don't look for a 2010 model, you look for a 2013-2014 model. The same is true for your computer. Even Apple folks who want to claim that this is not an issue for them will have to admit that the current Apple OS is 10 or 11 (which started out as 1 and then 2 and then 3 and then 4......) Newer is "generally" better and there's nothing at all wrong with Win8.
I guess what I am trying to say is that new is almost always different but that does not mean that it's bad.