Wow--they're both important, Lars. But if I had to pick one, it's the instructor. Without experience as a reference, most first-time beginners won't know if their equipment fits "right" (and at least as important, is set up right, and appropriate to begin with) or not. A good instructor is the guide to getting it right!
That's my final answer.
(But if you want me to argue the other side, just ask!)
Happy New Year, Lars.