"Best Burger" would be hard to rate since taste is subjective. I know a lot of west coasters who LOVE In and Out burger. I'm a big fan of Fatburger and 5 Guys Burgers and Fries. Burgers at most steakhouses are usually really good. Flemming's has an awesome burger as well. In my personal opinion though, if you have grill skills, no one makes a better burger than you.
So far, for me, m y favorite burger is from Cherry's Cricket in Denver CO. I've had burgers in CO, AZ, CA, Wash. DC, Virgina, FL, OR, CT, NY, RI, MI, NC, Canada, Mexico, Puerto Rico, Virgin Islands, and in the UK. Cheryy's Cricket is hands down the best I've been too.
Foodie burgers are a weird breed. You really can't compare them directly to each other the way you do with fast food because there's no restrictive price point and they each have their own character.
Think of it like trying to compare a NASCAR stock car to an exotic sports car. The exotic sports car doesn't have restrictions and weight limits like the stock car does. One is standardized to demonstrate the abilities of the driver and the other is what happens when you unleash the imagination of the designers.
I 2nd in and out burger, every time I land in Cali I generally go straight there from the airport. 5 guys here is delicious as well. We also have a place called "cheeburger cheeburger" that's good as hell.
I think In and Out burgers suck.... Would rather get a burger from Mc. D's.
I've had the Umami burger... Thought it was okay. I liked their Carnitas Burger better....
So far, I'm not too impressed with Cali food in general.
As far as burgers go.... Tap-In Bar & Grill in Grapevine TX was the best for me.
(Haven't been there in 5 years though, so who knows what it's like now days)