@Comic-Sans Hey - bit late to the party here, but incase you (or anyone reading in future) swings by...
I'm making an arcade machine of my own (albeit mini). After a first proto (enclosure for a 5" display and USB ports for a few retro USB controllers) I decided to make a slightly larger one (7in screen this time) - and I also wanted arcade buttons.

I got the EG Plays ones (specifically these: https://www.amazon.co.uk/dp/B075DFNK24 ) and I've been really pleased with them. The stick is sturdy and feels really nice. The buttons are perhaps a little cheaper looking than some, but they're really responsive too and look really nice when lit up.

That's not to say the Sanwa ones (which I don't know much about) wouldn't be noticeable better, but at the end of the day I see many of these things as things that could be upgraded. The dimensions etc appear to be somewhat standard across both brands (and others). The type of person who builds an arcade cab is likely a hobbyist - so I'm sure the EG buttons won't go to waste if you replace them in future with better ones :)

There's a single encoder board which everything plugs into (with extra connections for other bits, etc) and this goes straight out via USB. I had these all plugged in and tested in my computer within 5 minutes of opening the box.

Good luck!

Most standard button layout?