Maison Kayser is arguably the best bakery in Paris. This is a big claim to make, considering Paris is the capital of all boulangeries, but Maison Kayser is such an incredible place I can do it without a second thought.
The baguettes are perfect -- Parisians line up after work to get them -- and they're usually hot. They're crunchy outside, almost milky inside, chewy and light. The croissant d'amande is the best I've ever had -- pure butter and sugar -- yet somehow still light and delicate.
The walls are lined with beautiful bread of every variety, there are shelves of colorful tarts (which look like art, not food)... there are sandwiches, rolls, cakes... you name it. The only problem is choosing from the plentiful walls of delectable options.
Plus -- walking into the golden and busy bakery on a raining morning may be one of the most pleasureable experiences I had while in Paris.