I was told bully sticks are not a good option for puppies, what are your thoughts? 

I use bully sticks for pre-teething puppies. Once large breeds like GSDs get their adult teeth they often power through bully sticks very fast so I typically limit them to the first 5-6 months, depending on the puppy.

I also like to use raw meaty bones (knuckle bones, femurs ) that I get from our local butcher shop, always with supervision.