Kailh Speed Silvers vs Gateron Yellow
The Kailhs win here They are noticeably smoother as well as less wobbly. They're also quieter and less clacky than the Gaterons. TBH the Gaterons were kind of disappointing. They're not much smoother than these red Outemus I have.
Weird. I'm not a fan of gaterons by any means, but…
All Kailh Speed switches that I have are extremely loud ("clacky"). I blame the housings. I've tried the stems in genuine Cherry MX housings and they sounded normal then (quieter than gateron), but holy **** the Speed housings are loud.
(I was mainly interested in jailhousing Kailh Speed Gold, but not only it felt weird, the clack was overbearing, whereas my jailhoused Cherry MX Blues were very quiet.)
I agree that silvers are quite tight, not that smooth though. In my case, Gaterons wins, although by a small margin. Either way, nowhere near OG vintage blacks.
Gateron Brown vs Kailh Speed Copper
The Coppers are interesting. The tactility on both switches is quite weak but feels very different.
The Coppers have a very sharp bump right at the top. Gateron Browns have a more drawn out, softer bump. The Gaterons feel smoother to me in this case.
I honestly wouldn't recommend either the Browns or Coppers. The tactility is just so weak that it almost vanishes when you actually type on it a reasonable speed. If the Coppers were more tactile they would probably be a great switch.
The thing with Speed Copper is that it does have a quite pronounced bump, but it's very short… and sort of muffled in the original housing, I'm not sure why. When I put the stem in a Cherry MX switch, it suddenly feels kind of clearer; the bump also aligns with actuation much better. It actually reminds me of even more compressed Cherry ML with very long post-actuation travel. Or jailhoused Cherry MX Blue (using JSpacers), which are slightly mushier/grittier/whatever, but also quieter and not as pronounced.
I wouldn't even compare it to browns. Well, except Kailh Box Brown, which is apparently very close to Speed Copper, except with the bump moved closer to the middle of overall travel.
The problem with all those switches (compared to something like MX Clear and respective—usually purple—clones) is that the tactile bump simply disappears, when pressed rapidly or with more force.