If I want to migrate SharePoint Managed Metadata Termset to production from development environment what is best possible way? It can be done either as XML or as excel file as the intermediate. But which one is the correct way in terms of accuracy of the Managed Metadata in production? What is industry standard way?
There are some great 3rd party tools such as Sharegate that will do it easily for you. However, I just recently used a method using Word that worked perfectly. It's a bit of a hack, but it did the trick in about 5 minutes and was free.
Essentially, you create a new document library with a managed metadata column and save a Word document to that library. While in Word, you open the Document Information Panel and cache the term set from the managed metadata column. You can then save the cache as a .xml file and use a free xslt stylesheet to transform the xml into a csv file.
The whole process can be found here: http://www.metaengine.com/2012/02/Export-and-Import-a-Term-Set-on-Office-365-with-no-code