As an instructor I would tell you to take the car with stock high performance tires. As others have said, you'll learn significantly more in the begining with less grip. I would also add that if you search the forum you'll find that people have not been able to drive their Model S for more than 2-4 laps without it going into limp mode on the track. There is mention of this on the Nurburgring thread where the car can't even make half a lap of that track. Unfortunately Tesla has not built the cars to work well in driver education events that typically have 15-20 min sessions. Without being able to do more laps, you won't even be able to build much heat in "R compound" tires. Thus I don't think I would even bother with R compounds for a more experienced driver.
As an alternative there are many cars you can rent from mainstream rental car agencies that will work just fine for your first track experience. You can rent a 3 series BMW or C-class Mercedes and learn at ton.