The blog that is still viewed the most is the 'My Best Self' blog http://mybestselfjourney.blogspot.com/ the majority of the advert clicks came from there as well. I think this is a topic which really hits home with alot of people. Plus the nature of my blogging usually means I mention weight loss which ensures quite a few diet / weight loss adverts on my blog and it seems like web users are more attracted by these adverts than some of the others on my other blogs. For example my travel blog http://upupandawayadventures.blogspot.com/ has quite a few adverts for things like malaria advice abroad etc, very specialised and only really of interested to people who happen to be travelling to malaria zones in the near future.
So in summary it's much more productive to blog on a topic that is of interest to a large group of the online community.