While some folks, even some Chinese immigrants and some who are of Chinese descent, claim to prefer the food in the City, for truly next level Chinese food and even remotely authentic Japanese, elsewhere (i.e the point of origin) is really the best choice.
This requires a two-fold answer:
1) People prefer what they've become accustomed to; and
2) "Ethnic" foods tend to get stuck in time from the era of the mass migrations,and then typically westernized on top of that. I grew up eating west coast Cantonese-American slop, and didn't know any better. It is only in recent years (with new immigration) that a myriad of regional Chinese cuisine restaurants have emerged at a high quality level.
3) Some of us just "suffer" with the local fare, and can't always go to Japan when hankering for Japanese foods. I suffer accordingly, in an area that provides me with Japanese cuisine better than 98% of the USA. And, I'm more concerned with "delicious" than "authentic." I've said it time and time again - nothing could be more authentic than a bad restaurant in the country of the food's origin.
Accordingly, if someone wants "go to" Japanese-origin deliciousness in the East Bay, might I suggest Delage in Oakland (if budget isn't an issue) and Mujiri, for sushi take out (or a small dine in area now open). You wouldn't be disappointed, although the poster I'm quoting might only give it a "it's ok" until said poster and I have downed the third bottle of something Rhone, at which point, said poster might even want seconds!