Found quite the collection of Street Art in Chiangmai, Thailand so far. There are also some galleries and lots of tattoo shops so I'd consider this a pretty creative city.
I guess I like street art so much because it challenges the traditional idea of art being hidden away in a gallery or museum and/or only accessible to a privileged few. It's often a healthy dose of civil disobedience and it's up to the artists themselves and the public to deem what is art, not just a few critics or curators. As long as it's not outright offensive, and especially if it has a good message behind it that can provoke thought and conversation, I like that street art is free and always available to the masses.
Many times, I prefer it to the 'modern art' (ex. a straight up piece of rope nailed to the wall) or rather homogenous antique paintings that I've seen in legit museums. Don't get me wrong, museums and galleries are cool too but you expect to see art when you go there. I like turning a corner and unexpectedly seeing a mural like "Oh hai! Here's a little eye candy for you. You're welcome." If I find a few murals here and there, it becomes like a little urban treasure hunt and I always try to find more!