This is a great question. I think it greatly depends on what you aim to do in the locations you visit.

To answer simply, I would say Zermatt, Switzerland. I lived there for a few months back in 2010, and it really gave me an opportunity to see what sorts of things go on behind the scenes of a large tourist town. It's a beautiful place with wonderful people, and my time there certainly inspired me to more seriously take up filmmaking and mountain climbing. Definitely the most influential place I've been to say the least.

However I would say the place matters less than what you do to form a connection to where you are.