SharePoint migration tool

I think this depends a lot on your environment and migration scenario. Microsoft itself provides a tool for SharePoint Migration. ShareGate is among the most popular 3rd-party migration tools and the one I personally have most experience with, but there are other great alternatives.

I'd suggest you to search for articles comparing the most common tools, for example this one below:
https://collab365.community/sharepoint-comparison-matrix-for-3rd-party-migration-tools/