depends what you really enjoy. the best bet is to get two boards. one for park and one for riding.
also the park board can be split from jibbing to jumping. depends on your preference really.
if you are instructing... are you teaching tricks or are you teaching how to ride? i would cater the board to that if it's your job.
I am going to do a course for becoming an instructor in Canada in November and after that I will be working as a teacher for 4 months. But next month I am going to Germany and then I will already need my new board, otherwise I have to rent it.
Wish I could have 2 boards, but now I simply don't have the money for that.