I havent been to the South (Phuket, Crabi) but been pretty much everywhere else. Chiang Mai is probably my favorite, more chill but you can make it whatever you want. Bangkok is great but you lose some of the value that is so attractive. Buriram is so cheap, slow life but still plenty to do. Whatever you want is here so I would say bounce around. I need to explore Vietnam more. I still have to do Indonesia and Philippines.