What are some alternatives?
When comparing Syncthing and Mega, you can also consider the following products
Dropbox - Online Sync and File Sharing
Google Drive - Access and sync your files anywhere
Nextcloud - With Nextcloud enterprises host their own secure cloud solution for storage, collaboration & communication from any device, anywhere.
Box - Box offers secure content management and collaboration for individuals, teams and businesses, enabling secure file sharing and access to your files online.
SpiderOak - SpiderOak makes it possible for you to privately store, sync, share & access your data from everywhere.
ownCloud - ownCloud is an open source project enabling businesses to host their own cloud storage while maintaining regulatory and compliance needs.