Words of wisdom... 80%+ of EMS medical direction is Political and Situational Savviness... Statements like above can be detrimental to your EMS career.
The medicine is certainly different then what we do in a state of the art emergency department, but reasoning through prehospital practice is not terribly hard for someone who gives it some effort. The hard stuff is dealing with personal issues, administration, hospitals, and your community. At least that has been my experience....
I did not answer the OPs question, I think a system that gives you the most autonomy would be the best. If the fellow is dealing with the above, with the teaching staff giving oversight in the background, then it will probably give you a great experience.
For what its worth, I am not an EMT or medic and have no formal EMS training. Like many directors in the past, it sort of fell my way about a year ago. Lots of learning for me on the job, and I have met some tremendous 'mentor' types out there and find the EMS director community is always very open to helping anyone out.