Which niche for push notifications?

Hello everybody. I know there are similar threads below. By my ideas are a little bit different.

Since I work mainly with ClickBank, I would like to use cheap push notification traffic to create a new mailing list on getresponse.

Which niche would you choose?

anything that popular.

a niche should be something now.

cheek news, internet, Buzzfeed etc.

then cheek google trend.

soon get a correct answer.

This all comes under, understanding keyword research for marketing.

you might need to do some keyword research course.

there some keyword sellers in the misc try them, getting free idea won't help as there be popular generic