Cantonese, Hunan (Province just north of Guangdong) and Dongbei (Northeast) Cuisine are superb and the absolute stars of Ethnic Chinese food in China. Xinjiang cuisine is also excellent but obviously not 'Chinese' per se.
Southeast Asian Chinese food is easily the best however. Cities in the Archipelago with strong Chinese heritage like Melaka, KL, Penang, Singapore, Medan, Jakarta, Semarang and Surabaya all have traditional Chinese food cultures that rival Guangzhou and Hong Kong.
Yum Cha doesn't really exist outside of the South in China. I found a Yum Cha style restaurant near my office in Central China but it lacked Cha Siu Bao (Steamed pork buns) and thus did not really count. Very very disappointing.
Eating some Ketoprak right now. It's a grab bag of veggies and tofu served with vermicelli noodles in a spicy peanut sauce. Sublime.