I'm going to start teaching a photography club soon, but I was wondering, since I'm going to buy my film in bulk, what type of film to use??

When I started photography last year, I used Ilford FP4 125, the results were good as in perfect grayscale range.
But When I started experimenting with the loads of film options out there, I saw that the Delta brands were good.

So should I buy Delta 100, Delta 400, or FP4 125?