Northern California because there's literally SO much to do here.. Surf, Ski, Boat, insane mtn bike trails, and the weather is relatively mild all at the same time almost no matter where you are. The sun shines more often, and though it does get hot in the summer, You can drive 3.5 hours from San Francisco and be in Tahoe, or Yosemite, or some gnarly surf lanes up or down the coast. It's all relatively well-connected.
Plus, weed is pretty much legal here if you're not retarded about it - and SO much cheaper... (then again, the whole pacific coast has this luxury, so really the Pacific coast just rules)