Comercial CFD codes have the advantage of having been “tuned” to be robust for specific conditions, and even more, they are more user-friendly for a “click&run” methodology. On the other hand, they are a black box, one input one output.
Open source codes are more flexible, being possible to modify turbulence models, introducing new terms or modifying the existent ones, generating new variables for output, adapting the input for your CAD generators, or directly linking them with own-housing post-processing tools that at the end of the day are going to make your life as a CFD engineer easier. The disadvantage? The company/team does not need a “click&run” user but a development one. This will cost you more time and effort at the beginning, but having access to the source code of your solver means that you have absolute control on what your code is going to do.
Hope this helps