I find only Finance paying great income! however i am looking to test few of low rated keyword to gain more exposure because high paying niche is hard to compete with the competetion
You never know things are always changing so keep up on research. If you look on the "Google Keyword Tool" the payout to you per click is about 25% of the "Estimated Avg. CPC" and if you look on "SpyFu" its about 50% of CPC.
Loans, lawyers, cars, insurance, mortgage, credit cards, debt, forex, etc. But the best to earn is to work on sites/niche in which you have interest
Something you know, if you don't know much about the topic, it won't add up to much for you unless you research it and learn more about it. Go with whatever you know