Form Factor
A mini-sized keyboard is viable in most cases, especially for those that want to reduce deskspace and want the ability to fit it inside of a backpack. In all honesty, many keys on full-sized keyboards are duplicates or unnecessary. Although, for certain professions and uses, some keys will be beneficial (such as a the number keypad and a few others).
Gaming Keyboards
I wrote an article on this topic in the past, but no, buying a gaming keyboard will not improve your gaming experience over a regular (but still well built) keyboard.
Wired vs. Wireless
The aspect of wireless keyboards having latency issues is overestimated, in my opinion. It does depend on the reliability of the bluetooth signal from your computer itself, but otherwise should not be an issue once its connected. Occasionally, you may find the battery of a wireless keyboard dying during an important moment or an online competitive game, and that is frustrating. But if you can commit yourself to charging the battery once every 2-3 weeks for good measure, this should not be an issue. If you have a stationary desk setup, you probably won’t reap the benefits of a wireless keyboard. However, if you have other computers in your home or you want to use a living room desktop PC setup, a wireless keyboard does offer a lot of utility.
Mechanical vs. Membrane vs. Chiclet keys
Mechanical keyboards significantly better in terms of tactile feedback and usability than more affordable membrane keyboards. If you do a lot of typing, it’s worth trying out some keyboards at a computer/tech store to see which keys you like the most. Some have sample keys on display that can be pressed. Chiclet-style keys are not inherently bad, but it depends on the keyboard.
Backlighting is a worthwhile feature
It doesn’t need to be full RGB with a bunch of RGB features, but any backlighting at all is a very important feature. When using the computer at night time with the lights off, keys are difficult to see and require the user to focus their eyesight on the keys for a greater period of time if touch typing does not work. There are possibly some home-made remedies for getting a little bit of lighting to shine only on the keyboard, but for tasks which require consistent error-free typing (such as gaming), backlighting is very useful.
Charge Cables > Batteries
For wireless keyboards, batteries are a downside compared to detached USB cables that can just be attached at will. When they run out of power, you need to drop whatever it is you’re doing, remove the lid, charge the batteries (or go out and buy new ones), wait and then replace the batteries, whereas a charge cable can simply be plugged in at any time in a few seconds.