What is the "best" way to share a Power BI Desktop data model with others?

Email them the file.

Select File $-$ Share on the Power BI Desktop report.

Create a Role based on Row$-$Level Security.

Publish your Power BI Desktop report to Power BI Services $($PowerBI$.$com$),$ then give them access to the PowerBI.com workspace. Then they can access the data model from Excel, Power BI Desktop or PowerBI.com.