That's just wrong Dpcambo. That is just like deceiving people. In fact you are deceiving people. People are in this for the money and have NO passion, that makes me sad!
Some of the best niches be below my friend. Oh my, you are going to be rich now my friend. - paid surveys - work at home - medical transcription
There is no 'best niche' to get into, because AdSense works best with traffic coming from search, and once everyone and their brother is targeting the same niche because it's considered 'the best' there are going to be at least a few people who know what they are doing and rank in the top spots for a big bunch of the exact same keywords, after which the niche is just going to be a ton of work for very little money. Try to rank for high traffic keywords in some of the niches mentioned here. You can certainly forget about making much money.