For many years we have partnered with Sharegate. It is the de facto tool to do SharePoint migrations these days and offers great value for money. Sharegate has two products: Sharegate Desktop and Sharegate Overcast.
Sharegate Overcast helps you control and optimize Azure costs, and Sharegate Desktop helps with migrations and classic SharePoint Management.
The migration portion of Sharegate Desktop offers everything you need to support SharePoint migrations. It can be used to explore and create your inventory and to do dry-runs (“Pre-check reports”). The solution will effectively migrate all of your content without any volume restrictions. It is user friendly, looks fresh & clean, and doesn’t need much explaining to get started.
The management portion is also very practical. It will help you prepare migrations by allowing you an easy way to discover permissions and content locations. The solution also offers the possibility to schedule clean-up tasks, find content that takes up a lot of space, uncover inactive users and permissions, copy user permissions, and report on most aspects of SharePoint. In the new Sharegate Online tool, you can even set up alerts to get updates on suspicious activity on your tenant for instance.