I do not have a preference for either of the two options you name, they might have their pros and cons.
There are more options though that are not-for-profit:
Training courses organized by training platforms funded by large funding agencies.
Elixir Europe's training program is a good example:
Programs like TESS might provide a broader approach to researcher training and research schools, they make their materials available, aggregate courses and might provide a rather unbiased overview in comparison to the for-profit training model. They might also be more cost-efficient for the individual researcher than commercial training options.
Disclaimer: I am working on a project partially funded by the Norwegian Elixir Node. Feel free to ask me anything about researcher training and access to courses.