Maybe it's time to post some thoughts on this question (which comes up a lot):
- Unlike other foods (pizza or ramen for example), sushi is an "interactive" experience. It depends a lot on what you ask for and how well the itamae knows you and understands your likes. This is no news, of course, but I'd almost say that the "best" is the sushi restaurant you go to the most often. Not quite, but really a big factor. Saving up to go once in a lifetime to Urasawa may not be as satisfying an experience as repeat visits over many years to a place you can afford.
- As we know, where you sit actually has an effect too. "Table sushi" will never match counter service, for example. Neither will being served by an assistant instead of the master.
- Unlike other eating experiences, how you go about eating and how well you observe table protocols affects what you actually taste. Obsessively dunking everything in a vat of shoyu, for example, most of which will eventually go to waste, will ruin any subtlety of taste.
- Perhaps because of these "rules", who you share a sushi meal with also has a big influence on the overall experience and taste.
- The knowledge and prior experience you bring to the table (or, more accurately, to the counter) will modulate how you appreciate what is offered. It's important to seek the sushi bar that best matches your level of "expertise". If you taste no difference between fake wasabi (prepared from powder) and the real thing, no reason to spend extra.
- How closely you observe the taste of things will also make a difference.
It's often that people get lost in conversation and won't pay attention to the carefully crafted mouthful which is gone in seconds.
So, to answer the question of what is the "best" sushi can be complicated. True, the skill of the itamae, the quality of the fish, ambiance etc are factors we consider in recommending a sushi restaurant. But that's only half the story. And that's unique to sushi.
A more useful question might be "where is the sushi that I can appreciate the best at this time?"
Which opens it up to a discussion with more questions - like what have you liked in the past and what can you afford on a monthly basis etc.
Sometimes, the best sushi is to be found close to home. Not because of any legendary status but because we the diners will do our homework and gain the respect of the guy with the big knives. He is there to teach us and it's for us to decide if we already passed that class and are ready for the next level - or not.
Sometimes to get your money's worth for what you really want - good quality, fresh sushi/sashimi you may have to go out of your way. My personal favorite is this place:
Koisan Japanese Cuisine
Sushi and Japanese - 1132 E Katella Ave, Orange
I've never been disappointed with my order in the restaurant or the sushi bar.