Most of the fancy switches you see people putting on their custom boards are shiny and new, but some of the most sought-after switches are older than the people typing on them. Because the tooling and manufacturing processes for switches have changed over the years, older batches of switches can have noticeably different properties. That's the case with the popular Cherry MX Black. Finding a batch of so-called Cherry Vintage Blacks is like hitting the custom keyboard jackpot.
The MX Black is one of Cherry's oldest switch designs, introduced back in 1984. It's a medium-weight stiff switch that falls in the linear category. That means there's no click or tactile bump as you press the key. MX Blacks were popular in industrial equipment, mainframe terminals, point-of-sale machines, and scientific instruments. The MX Black actuates at 60 grams of force and bottoms out around 80 grams. That's substantially heavier than the more well-known MX Blue (about 50g and 60g).
Cherry has been producing MX Black switches continuously over the years—you can still get brand new boards with fresh batches of Black switches. However, enthusiasts who have tracked Cherry's manufacturing report the company made some tooling changes around 1994 or 1995, and MX Blacks haven't felt the same since. The newer switches have the same force ratings, but they just aren't as good.
A Vintage Black is smoother and has less wobble. Some may disagree on that, but I think the difference is pretty noticeable when you've used a Vintage Black. You can see a comparison of vintage and newer MX Black stems below. It's hard to spot the differences in images, but the vintage stem is smooth, whereas the newer one has a slightly rough texture. The stem is what moves up and down in the housing to hit the metal contacts. If your stem is not smooth, the switch feels "gritty."
Some enthusiasts also claim vintage switches have better housings that reduce resistance, and that the springs are more consistent. I think those are less verifiable than the changes to the stem. Whatever the factors may be, these switches feel better than new MX Blacks.
Getting your hands on Vintage Black switches can be tough. The only source of them is old keyboards. Cherry provided the switches for a lot of WYSE terminals back in the day, so enthusiasts will snap these devices up when they show up for sale. Just desolder the switches, and you've got a batch of Vintage Blacks. You can always check the manufacturing date on an old keyboard with Black switches to make sure it's from the early 90s or earlier. That's the only way to be sure those MX blacks are using the original, better tooling.
If you don't want to dig through mountains of discarded retro keyboards, there are usually folks selling these switches in places like the /r/MechMarket subReddit for around 50 cents each.