Apple is due to their walled manicured garden philosophy quite the pain in the posterior to deal with as far as releasing apps on iOS is concerned. You'll need an Apple ID, an Apple Dev account (100USD a year just for that), a Mac in order to obtain the initial app provisioning certificates and dev certificate and a moderately recent Mac to compile the iOS app on. All in all it adds up to quite the little investment. And you are not done jumping through hoops. If a test version and you want specific people be allowed to test your app, you need their AppleIDs and deviceIDs - and sign the app with a certificate that contain these. Or by signing with a testflight certificate, and then manually invite users using email. Then you have to upload the app through a specific app on the Mac, and release for testing. Don't get me started on the review process...
On Android, if releasing to Google Play store, you pay 25USD - once - for a dev account, and that is about it. Any PC and OS will do as far as getting the Google Play app certificate. Compile with certificate and app-icons, upload to Google Play, wait for a mostly automated review process (takes a few hours) and done. For pre-release testing, just compile an unsigned .apk and distribute yourself for the testers to side-load onto their Android device. Couldn't be simpler.