Hi @Shri-6058 ,
Since your total storage content is 50GB, which doesn't reach the limits of SharePoint and OnDrive, both are fine, and content from SharePoint can be synced to OnDrive at any time. SharePoint library makes it easier to manage user permissions for files, and OnDrive is more similar to File Explorer.
Best practices for migration as JimmySalian says, migration tool(SPMT) is the most practical.
For the length of the path, you can see the restrictions in the official documentation. My advice is not to rewrite the path, but to change the file location to shorten the path.
Reference: File name and path lengths
In addition, although 50GB does not exceed the storage limit, it is limited by the number of items in use and performance is affected. It is recommended that you do not store all your data in a single library, as you may encounter a list view threshold error when the list view displays more than 5000 items.
Here's an article on managing a large library for your reference: Manage large lists and libraries
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