Hi and welcome! To answer your question, you should see what his interests are.
Generally, speaking-most of the members go with the 32 gb to stay on the safe side. That was my decision as well. I was worried that the 16 gb would be too small after using it for a year. However, now with the icloud---that allows for 5gb of storage as well. Some things to consider.
I am sure that others will chime in, however, if you are interested in some information right away-there are numerous threads that have already been posted regarding this exact question. You can use the search function to find what you are looking for.
Good luck and hope that you can come up with some information. Your BF will love you for it!!