Image and Media Best Practices
Use media_entity. End of discussion.

People are actively working on getting it into core and once that happened, there is no reason to use file_entity anymore.

We (as in me and @slashrsm/MD Systems) will continue to minimally maintain it, as we have a number of big sites (a distribution actually) that relies on it, but it will most likely never get out of alpha while media_entity is already stable.

We're actively blogging about the status and progress on getting media into core:


http://www.md-systems.ch/en/blog/md-systems/2017/01/09/current-status-of-media-in-drupal-8-core-and-next-steps
http://www.md-systems.ch/en/blog/md-systems/2017/01/30/media-initiative-is-official-and-we-are-one-of-its-leading-parts