Sometimes choosing a niche to adsense blog will little difficult. But here are some ways that you could possibly consider to help you choose a niche that suitable for you.
This is my result of a long time research that I've been tried in internet marketing.
1. Hobbies / Interests / Talents.
Yup, if you write according to what you like, then you will be happy to do so. Noteworthy is, if hobbies / interests / talents you are not a marketable niche, then you have to be patient until they get a satisfactory result.
2. PPC Niche
For example insurance, forex, etc. Well, this niche is very tough competition. But once you get a good position, then the result is very satisfactory. But to get there you need to fight and (possibly) large capital anyway.
3. Less Competition or Targeted Niche alias Microniche
Niche like this can be found by using yournextniche.com, or you can see the product of clickbank. So also can see the products of amazon. Arguably less competition because it is less sought after. If you want to get satisfactory results, then you have to take a lot microniche.
4. Niche with Highest Bidding but Less Marketable
Examples: gossip, entertainment and news. Many people are looking for, but yes just simply looking for, not necessarily to buy. Niche crate is less noticed by the advertiser, so just be satisfying when you've got a big traffic (perhaps million). If you can make a google news site, it can certainly satisfactory results.
5. Hot Niche
This is in my opinion the most recommended. Examples of food, fashion, health and other niches. You need to explore your brain to get a solid hot niche. Good luck!