I still favor 7 over 8 personally. I have a windows 8 machine that I've run a UI customization on that makes it look pretty much exactly like windows 7. There were some really nice improvements to the core of windows in Windows 8 (and 8.1), but the user interface is terrible and unless you have a touch interface it is still clunky, even with the 8.1 updates.
Windows 8 is the next Vista/ME. Businesses will not be upgrading to the software due to issues and the cost associated with retraining everyone on the new user interface.
Why Microsoft forced this change is beyond me, they are alienting the people they actually make money off of, corporations.
That question can't be fairly answered without knowing what you use your computer for. If you use your computer mostly for consuming content (web browsing, watching videos, listening to music) then likely 8.1 is appropriate (although I personally find 8.1 horrendous). If you are a content creator then I recommend Windows 7.