1. A usecase that benefits me. eg bank, maps, uber...
2. A buzz about the app. eg. Instagram, clubhouse..
3. Curiosity based on reports or reviews. eg opencamera, snapseed
4. Advertising that hits home. eg. Camo,
5. To encourage alternatives. eg. Koo, Blusmart
Word of mouth.
If 5 closest people I know are using it, I might install it.
Playstore / app store listing copy & creative have zero impact on the decision to install an app.
I may install a new app based on the recommendations of friends, reviews, or if the app looks useful and has friendly interface. Additionally, I may install an app if it is free or offers a free trial period.