My Dad took me to Stan's Donuts in Los Angeles last weekend. I had a jelly donut and a peanut butter pocket. It's a damn fine place and we met Stan, the owner, who is quite the card.

http://www.stansdoughnuts.com/

Try Malasadas in Honolulu.

http://www.leonardshawaii.com/

I do not usually eat donuts but theirs was so good that I had two with cinnamon sugar - no fillings (for less guilt).
Yummy.

+1. worth lining up for 45 mins for.

Try Donna's Donuts in Flint- the best in town.

coffee and donuts at per se or the french laundry, duh .... :p

krispy kreme

no gamble at all
 

I like Ronald's Doughnuts in Las Vegas. At least half of them are vegan which works for me. I especially like the maple, coconut and oh so many flavors. Also good vegan jelly rolls. I love this place.

Another vote for Krispy Kreme!

As far as chain's go, I grew up going to DD every Sunday with my dad and later Tim Horton's when we moved to Buffalo. I slightly preferred DD over Tim Hortons for doughnuts and the other way around for the doughnut holes. I came across my first Krispy Kreme as an adult and never went crazy for the hot doughnut thing. IMO, the cake doughnuts at Dunkin Donuts are much better than Krispy Kreme. The yeast doughnuts at each place aren't comparable. I feel like they are two totally different products and recipes.

But I wouldn't necessarily call either place "the best doughnut." Doughnuts aren't something I've really seeked out to try while traveling in the US so I haven't noticed as many non-chain places compared to other food categories. I'd love to look for them and try them out, but my scale already hates me for my other secret food indulgences. :(

Tasty Bakery in Graham, North Carolina. We had an assortment of those, Dunkin Donuts and Krispy Kreme at work last week and the Tasty Bakery ones were the clear winners.

Searched to see if this had been mentioned. Top notch doughnuts.

Another vote for Voodoo in Portland!

Hara Donuts with about 20 branches around Japan !

http://haradonuts.jp/

Another vote for the Doughnut Plant (NYC):

http://www.doughnutplant.com/

And Dynamo Donuts (SF), especially their Maple Glazed Bacon Apple doughnut:

http://www.dynamodonut.com/our_donuts.html

Krispy Kremes: last time I had some was in Korea in a basement area food court. --We had coupons for free donuts, too. Then there is Leonard's malasadas in Hawaii --yummy with cold milk.