I used to work for one of the keyboard brands doing consumer research (won’t say which one, but will say I’ve seen a lot of keyboard users).
The market and choices are somewhat simpler than they might appear. It is an enthusiast market that gets overloaded with jargon that most folks can ignore. Following are a few questions and tips. This is all top of head and only my opinions, but I hope it will help to simplify the choices! I will assume you don’t seek an ergonomic keyboard, as that is a specialized market.
Q1. Will you use it for gaming, or only for writing?
A. If not for gaming, then IMO you can ignore any that specify they are for gaming, have lights, etc. I’m not saying necessarily to avoid them; they are OK and you can turn off the lights if you prefer. Just ignore that they are for gaming. (Or avoid them if that makes things simpler.)
Q2. Do you want a small audible+tactile clicking sound like an old IBM PC keyboard?
A. If so, you want “blue” switches. If not, then you want “brown” switches (or, if you want it for gaming in addition to writing, then “red” switches). If you’re unsure, get brown switches. Brown switches are still tactile to feel the feedback as you type, but they don’t make the clicking sound.
Q3. What about “cherry” and “customizable”?
A. Ignore them. “Cherry” is a brand name for one manufacturer of the internal switches themselves (not a specific color). They make excellent switches for premium keyboards, but for most purposes, just choose a keyboard brand instead (as noted below). Similarly, ignore “custom” and “customizable”. Those options are for folks concerned about special purposes such as intensive gaming and IT usage, or who are expert and picky keyboard fans.
Q4. What else?
A. You’ll have a few other choices:
- TK (has a 10-key number pad) or TKL (no number pad), aka tenkey and tenkeyless. Personal preference with no particular recommendation (although I like TKL for its small footprint).
- Wireless or wired. For writing, I prefer wired because wireless keyboards have lag, drop outs, and batteries. But again, personal choice.
- Size. This is one to watch out for! Some keyboards sold online are 70% size (or thereabouts) and intended for specific audiences such as gamers in Asia. Make sure you get 100% key size. [Added note: some also use “75%” and similar to mean tenkeyless, and that is not something to worry about. Yes, it is confusing. Read the reviews and look at photos if unsure!]
- Brands: to simplify, I’d suggest to go with Keychron or (if you see a good deal) Cooler Master as initial options. Reasonably priced and reliable.
Q5. Can I try one?
A. Visit a large PC retailer and they may have a few but not the brands above. Retailers are often paid by brands to stock items and thus emphasize pricy & marketed manufacturers (like where I used to work 
). However, the odds of finding the exact combination you like in a store visit is small because there are so many options. I’d order one instead from an online retailer with good return policy.
Q6. So which one?
A. Mix and match the attributes above for what you might like. For example, search phrases like:
- Tenkey blue Keychron wireless mechanical keyboard
- Tenkeyless brown Cooler Master wired mechanical keyboard
- Tenkeyless red Keychron wired mechanical keyboard
- etc
FWIW, I’m currently typing on a ~10 year old TKL [no number pad] blue switch [clicky] wired Cooler Master keyboard.
Overall, I would highly recommend to buy one and try it. As others note, once you get used to a mechanical keyboard, it is difficult to go back!
Again, don’t worry too much over the choice, if it is returnable. Personally, I have used many mechanical brands and have been happy with almost all of them, whether blue or brown, TKL or TK, from any reasonable brand. No need to spend $hundreds until you have very specific tastes. Most products in the range of $50-100 and up should be quite good and IMO will be far better for writing than any membrane keyboard.
