I generally give people things I'd like to have. This year everyone's getting an iFixit Pro Tech Toolkit. They might not need it now or ever but I like encouraging self repair (and often "self" ends up being me).
I do a lot of photography. I know exactly what I want, I'm damn picky about it, and I don't want anyone buying gear for me. I know other photography enthusiasts and they have things they want, and it's not the same stuff that I want.
In general I'd steer clear of the other person's hobbies unless they have at some point stated exactly what precise product they want.