1. if you want to make money start on a searched topic
2. if you want only to become a blogger start on a topic that you are like. This way you will have then more 3 topics on your blog. :)
The more popular the niche is, the more competitors that you got. If you will be a newbie blogger it is best to start on what field interests you the most so you can start immediately and not get discouraged by the pros.
Its about quality content, it will be hard to make quality content if you have limited knowledge on the subject or you are not passionate talking (or blogging) about it.
I know that the best paying niche for a blog, that is regarding adsense ads, will be real estate and health industry.
If you blogging to make massive money then here are the best thing to blog about Real estate investing, Internet Marketing, Network marketing these are the most popular niche out their.