I've been a long time lurker. I was really happy for a time with upgrading my anne pro 2 cosmetically with key caps and cases. I then ordered a the gk21 numpad which is hotswappable and started me on trying switches. I havent tried much as I haven't purchased a tester. I think i'd rather just order a 10 switches and put them into a plate or throw them in the numpad which has been great for testing. So far I've tried Gateron Blue, Brown and Yellow. Kaihl Brown, Burnt Orange and Pro Plum. I've ordered Halo clears and have done nothing with them. I looked at a picture and thought they would work with my dz60 which i stupidly soldered leds to the pcb, as I didn't like the burnt orange and also made my hot swappable board not so swappable. Now i have purple trash pandas coming and who knows when my switch opener will come. So next up in the DZ60 will be the stock trash purples. I currently have stock yellows in which i definitely enjoy over both variations of browns maybe I like linear after all. I first went browns that came with the anne pro 2 and knew I wanted something heavier and started looking into other keyboards. Blue was my next switch and it felt great but i couldn't do clicky. Orange was ok, Pro Purple was too heavy for me.
I'm really happy with my Dz60 I mill maxed for multiple layouts it has allowed me to try out a whole bunch. I ordered mine from KBDfans unassembled of course the DHL shipping got it to NY in a week and a half. but yeah recently it has been a nightmare getting materials for building. hope your pcb comes soon.
That gk21 looks like a fantastic platform for that purpose. Honestly, I would want a tester and a hot swap board. I can't imagine it would be easy for me to track down every single individual switch I have in my tester without ordering it, and the switches practically just fall out, so you can throw them in whatever from there.
Gateron yellows are probably the ones that leapt out at me the most of the ones you have named that I have tried, which is pretty much all of them you named other than the Halos or trash pandas. Nice and smooth, and a good balance in weight between red and black. Nice linears, for a guy who doesn't particularly like linears. I certainly like them more than MX (or clone) clickies these days, and I'm a clicky guy. What was it about the blues that you couldn't do? The Kailhs you tried were the standard variants, not the box design? I think the Gateron browns are probably the best of the brown siblings of the ones I have tried, but they're still only just so-so in my book. I imagine the pandas or halos will suit your fancy much better, but of the ones I have tried, the Kailh box tactiles (especially royals) and (surprisingly) MX clears are the better modern tactiles I have yet felt myself. If either of those are too heavy, you could swap in lighter springs. I believe with MX clears that's what's called an ergo clear.
The best modern clickies in my opinion (in terms of feel and sound), which may now be controversial since I added Matias to the front runners, are Matias' "tactile" switches and Kailh thick clicks, especially the jades and navies. Matias comes very close to the SKCM Alps of old (their direct ancestors), which are kind of king of the hill for clickies, with capacitive buckling spring, and beam spring (best of them all, if you want to drop $1,500+ on a single keyboard). Kailh's click bar switches, which come in various weights and levels of tactility, are very sharp and crisp, while some like the pinks and jades still remain relatively bassy, like Alps and Matias switches.
My favorite tactiles are also old complicated Alps switches, although I didn't get a long time to play with them. I hear good things in this regard about Matias' "quiet click" switches as well, although those are apparently potentially considered even less reliable than their clickies, which have a reputation for developing chatter. Mine is still working perfectly after a week straight of daily use, so maybe Matias has gotten their act together.
I think I ordered mine on Aliexpress, so from what I'm reading now, it may not even be an authentic DZ60. lol. Oh well, I'll see. I believe the retail offering for hot swap on that board is kailh hot swap sockets. What did you go with your own mill-maxes for, in particular? I may have to do the same, since I ordered the mini USB version, since I hate type c and micro, which wasn't offered in a hot swap configuration at all. I don't even know if that board supports kailh sockets.