Update 4:
Finishing up our wonderful SF trip, we stopped by this morning to go out with a bang at our favorite Croissant in the city…
Arsicault Bakery (Revisit)
Getting there right as they opened, there were already 4 people ahead of us.
Croissant:
Time from Oven: 15 minutes.
Taking a bite… there is the same crispiness, airiness, but something is wrong. The deep, fragrant, wonderful Butter flavor is gone! Arsicault used to use a combination of French and Irish Butters and while not as deeply, stunningly buttery in a way that only certain French Butters can be (at Chaumont), but today, it was just plain and very muted! 
We quickly went over and asked the manager, and she told us Arsicault has now switched over to an American Butter! Noooo! 
This is a huge downgrade in flavor (the ironic part is that she told us, “We decided to try the cheaper American Butter and felt there was no difference, so we switched.” 
Wow.
Major Downhill Alert. (@ipsedixit @PorkyBelly @BradFord @beefnoguy @Bookwich @T3t @Ns1 @attran99 and others)
So for a very good, but muted Butter flavored Croissant, Arsicault will still scratch that itch, but we’ll be saving our calories for Chaumont (and if in the area when they come out of the oven early, Konbi). A sad day. 
Almond Croissant:
Their Almond Croissant has a nice crunch, not overly sweet, and I love their Almond Paste filling (not overly synthetic tasting like some versions we’ve tried). However, it is not as good as @Ns1’s Lou, The French on the Block, nor Chaumont, but it’s very good. 
Arsicault Bakery
397 Arguello Blvd.
San Francisco, CA 94118
Tel: (415) 750-9460
B. Patisserie (Revisit)
We had some improved Pastries the last time we revisited B. Patisserie, from Pastry Chef Belinda Leong (former Pastry Chef of Manresa in Los Gatos, CA (Michelin 2 Star)) and Michel Suas (Pastry Chef at Restaurant Barrier (Paris, France) (Michelin 3 Star)), so we were hoping it would continue to improve since our last visit.
Almond Croissant:
This was a touch too sweet for me. It wasn’t bad, but Arsicault’s was definitely better, as was Tartine Bakery (SF)'s Almond Croissant the last 2 times we tried it. Definitely a step below Lou’s and Chamount’s, but if you like your Almond Croissants more sweet, this is the version to get.
Kouign Amann:
Now this is more like it! 
Crisp-crunch outer shell, nice buttery inside, this was delicious! By far the best version we’ve tried now at B. Patisserie (1st time was stale (terrible), 2nd time was better, now this). Having just had Pastry Chef Karen Hatfield’s Buttercup at Sycamore Kitchen in recent memory, we like her version a touch more (and it’s also been more consistent (3 times, all consistently well-made)). But this is outstanding now, and hopefully the norm. We’d be glad to stop by and get more of these next time. 
Black Sesame Latte (with Almond Milk):
Oh yah! For Black Sesame Lovers out there (@paranoidgarliclover), definitely a unique morning alternative to Coffee and Mocha Latte’s etc., I love B. Patisserie’s Black Sesame Latte (w/ Almond Milk)! It is nutty, aromatic, and has a beautiful Black Sesame flavor, while still warming you up like a Coffee or Tea in the chilly morning, just differently. Must order for Black Sesame Lovers!
At this point we had one more stop before it was time to fly home later today…
B. Patisserie
2821 California St.
San Francisco, CA 94115
Tel: (415) 440-1700