It's the dual licensing thing I like about the GPL - you can be about the freedom, while still keeping a money making opportunity.
I also like how it makes a stand on the freedom issue, a strong one. The BSD license is the one I loathe and despise. It puts an annoying restriction on you, without gaining anything for the author. A proprietary license gets the author money. I respect that. The GPL gives the author his philosophy. I respect that. The Boost or zlib licenses say "whatever". I respect that. The BSD license says "whatever... but drop my name all over the place!" That annoys me.
