Because a) I've used IBM buckling spring keyboards and b) I've tried a lot of them on displays at shops. There were also switch samplers on display, so I was able to do side by side comparisons.
My requirements were clear. Light, some feedback, not so noisy, which is squarely brown.
Caps were easy. Put your fingers. Write a Hello World code, see how it feels. Is it alright? Done.
I've used ~15 keyboards in my life, if not more. I know what I like and I'm looking for.
Good for you. I ordered a switch sampler online and 2-3 keyboards until I found one that works for me. It's hard to know what you'll like unless you use it for a few days.
For example I have a heavy + linear keyboard, I was originally disappointed by it but I grew into it in a few weeks. Now I love the energy I get from the rebound of the keys.
The caps matter too - full height, half height, flat or with a small depression in the middle, various types of plastic, with painted symbols or injection molded symbols for light transparency.