Asking for this is probably not going to help you make any money. You need to think about what people need / want and give that information to them in the best possible manner. One only need look at the world to discover where money can be made. Lawyers and Doctors make good money in the US so issues based on law and medicine would be some of the higher paying niches. Insurance is another since there are so many various parts of our daily lives intertwined with insurance needs, Car Home Life Health etc. Financial - We're on the subject of money, and as such this is often a high paying niche. However these answers won't help you much, because in order to be successful, you need to love what you do and do what you love, and if you can't determine what will pay well, then this is probably not your love......
Take these into consideration : content and its potential , its update frequency , geographic location of visitors banking , lawyers/legal , insurance , travel , discount offers / rebates are top5 niches
Adsense Earnings= Traffic of Niche X Adwords Payout If you have a high amoount for both of these you strike gold