More Money Than Sense:
Model F or Beam Spring keyboard from New Model F, it is the only way you're going to get a vintage keyboard with N-key rollover
I Want A Metal Keyboard:
Keychron Q series keyboard of your preferred layout, Monsgeek M series keyboard of your preferred layout (Monsgeek is cheaper)
I Want A Plastic Keyboard:
FL Esports series keyboard of your preferred layout (CMK is their "deluxe" brand, most other naming schemes are similar to Leopold), 8bitdo mechanical keyboard of your choice in either full-size or TKL with optional numpad + calculator
I Want A Plastic Keyboard That Isn't Expensive:
CIY X77 (TKL), basically anything by Redragon

Best switches by type
>light linear
Dog shit switch type, reconsider your life
>medium/heavy linear
Gateron Oil Kings, Gateron Yellows
>light tactile
Kailh box brown v1
>medium/heavy tactile
Boba U4T, MMD Princess tactile, Chosfox Voyagers (Voyagers have clearance problems on taller keycaps like MT3)
>silent tactile
Boba U4
>light clicky
Kailh box white
>medium/heavy clicky
Gateron Melodics, Kailh box jade & navy

Best keycap profiles are MT3 (only buy on BOGO sales for best value and preferably buy the PBT sets like /dev/tty), Keychron KSA, and Akko ASA for shorter keycaps. Cherry/OEM profile is total fucking dog shit

ABS vs. PBT is purely up to preference, ABS feels more "hollow" and polishes from finger friction over time, but some people like this look and feel. "Doubleshot" means the piece of plastic is injected twice all throughout the keycap, if you cut a keycap in half you will see its legend distributed through the entire cap and the underside will have two-tone plastic from this second injection

Avoid any keyboard that doesn't list "hotswappable" or "hot swap" capability, these hotswaps are socketed ports on the PCB for switches to be easily taken in and out. There is no mechanical advantage to direct soldering switches in

Avoid "mechanical feeling" or "memchanical" keyboards like the fucking plague