There are multiple reasons and considerations when selecting an automation technology for your mobile app. The considerations would include
The mobile app platform in question - Android, iOS being the two main platforms
The learning curve for implementing a test automation framework using the given technology
Support available for the given technology e.g. While Espresso is backed by Android/Google and XCUITest by Apple, Appium has a host of sponsors who are supporting the active development of the technology
Flexibility of use