I suggested Stack Overflow on premises for my employer. The result is that I was allowed to set up a open-source Q&A-Platform for the company and if the acceptance is high there might be a budget for Stack Overflow on premises.
Since there is no real open source alternative to Stack Overflow in my opinion (yes, I'm a fanboy), does Stack Overflow have a data migration tool from one of the open source Q&A platforms so that you can easily switch to Stack Overflow on premises later? (platform -> Stack Overflow)
I know there exist alternatives to Stack Overflow. Currently I'm considering the following platform: