To me (I know, I'm stealing the question from Catwho), homebrew is often superior to commercial because it's unique, personal, and you can make it however you want. There are, of course, some microbrew and craftbrew locales that can offer quite a competitive option if they have something that you like, but you lose some of the pride and fun of having made it with your own two hands. Also, the alchemy (for lack of a sufficiently fun alternate term for it) of brewing is just FUN!
I also take the opportunity to explore all sorts of concoctions that can be made; for instance I also ferment mead and if I do say so it is delicious