I have data in a file geodatabase table that I want to write into an existing table in SQL Server (not enterprise-enabled) using Python. I am already using pyodbc to read SQL data elsewhere, but am open to using a different module to write this data. What is an example of the best practice to do this?
Give you have a connection to the SQL Server database already you should be able to make a connection pretty easily. You can then use the Copy Rows tool which will do the work for you, e.g.
input_data = '/path/to/data.gdb/featureclass' output_data = '/path/to/connection.sde/tablename' arcpy.CopyRows_management(input_data, output_data)
According to the docs any non-geometry column will be copied.
If you need to subset the original table columns, you can also create a table view first and use that instead of the original table.