brim and a few moments with an exacto knife is what I used. or one of those debur tools.
a very handy tool....
https://smile.amazon.com/dp/B07JGVDRQC
using a raft, or vertical with supports will give a worse result I imagine and more time to clean up.
also check out the ironing setting In Cura for a better top finish. but some may like the pattern.
Okay here's what I would do if i had a deck, the B sticking, and total confidence in my abilities:
Disassemble the deck, take a de-burring tool made specifically for plastics and gently de-burr the inside of the "B hole" in the face plate. (Inb4 some kind of Bill Burr butt joke)
If the issue is coming from there you'll solve it completely. You could probably get a similar result with the finest grit sand paper you can find maybe wrapped around a pencil so you can gently remove material from the cover so the B button can slide through uninhibited.
I'm personally terrified of the prospect of the tear down on the machine i haven't even been able to purchase yet but that's what i keep thinking of when i see these. Just a little extra finishing touch. deburring/chamfer tool
I like this one. I bought 3. The first for me, the second for my friend with an ender 3, and the third for me when I leave the first one somewhere random and forget.
Commonly known as a swizzle stick amongst machinists I know. It's one of a few different types of deburring tools. I've never seen one used in a slow mo glamor shot before. Made me laugh. https://www.amazon.com/VASTOOLS-Deburring-Chamfer-Removing-Aluminum/dp/B07JGVDRQC/