This depends on the requirements of your migration, specifically the number of users and the platforms you are migrating from.
For less than 500 users, that do not require data to be migrated from File System, GroupWise or Lotus Notes, we recommend CloudM Migrate Hosted.
For anything larger or with a File System, GroupWise or Lotus Notes requirement, we recommend CloudM Migrate Self-Hosted.
For more information on features, click here for Google Workspace and here for Microsoft 365