LasthumanAll those switches would work with custom keycaps, but I’d recommend staying away from BOX switches until we know for sure they’ve alll been fixed. They were causing damage to caps.
I’d recommend Halos since the resale value is high if you end up not liking them. For example, 70x Halos = $70-80, while 70x Kaihl = $15-20
LasthumanMost of the custom keyboard market is based on the same stem/cap standard known as MX or Cherry MX. These switches and caps follow that standard so you could get almost any other keycaps to put on these switches.