Out of the ones I do watch:
January CBB - CBB13 and CBB15
Both brilliant series, but I preferred CBB13 much more to CBB15. CBB13 also being my 2nd favourite CBB series. So 1 point to 2014.
Civilian BB - BB15 and BB16
Both civilian series have been absolutely dire. But BB15 edges it slightly for me. Another point for 2014.
Summer CBB - CBB14 and CBB16
No contest. CBB16 amazing series. CBB14 trash. 1 point to 2015.
TA - TA10 and TA11
Having watched TA10 a few weeks back, I think it's much better than this years series (which is decent at best). TA10
2014 takes this one.
IAC - IAC14 and IAC15
Now this one is an unpopular one as last years series isn't too popular on here whereas this years is often regarded as "the best since 2012". But I have to be honest, this years IAC failed to grip me. I found myself missing a few episodes and not caring. There were good characters, but I just couldn't be arsed with the show. Maybe it's the show or maybe it's me idk, but I felt a lack of excitement with this year as opposed to previous years, so I'm going with 2014 for IAC. As I enjoyed/committed to it more.
4-1 to 2014. The only thing 2015 did better this year was the summer CBB imo. Some would also say IAC, but not for me.