Switches: I hate clicky or linear switches. Even the low tactility of Gateron Browns is better than a linear, or a clicky. I prefer to listen to music while typing, and not silly clicks and clacks. So do my colleagues and my wife at home.
Keycaps: I hate DSA and other uniform profiles. Uniform R3 SA is just as bad as DSA. They are a pain to type on. I also find artisians awful, ugly, and stupid. Legends are also useless, and sets would be so much better without them - or non-alpha legends, purely for decoration.
Keyboards: Any keyboard that is not split, or concave like the Advantage is something I never want to type on (unless I end up doing steno, for which a Planck looks like a good choice, but that is chording, not typing so...). But even more than traditional keyboards, I hate split ones without proper thumb keys, or split ones with traditional staggering. Absolutely despicable those ones.