It depends a lot and you have to remember, most people really haven't tried a lot of boards, of a given size, I've often only had a chance to use one.
Full size/size is no object - IBM Model M, the granddaddy.
It's loud, not so great for gaming, and it's MASSIVE... But that feel! And then there is that durability... Even the newest are older than most GH members.
Slim full size - Logitech Illuminated. Very compact for a full size, light, backlit, one of the best scissor switches ever made.
TKL - Filco
It may be no frills and expensive for what it is, but it's extremely well made. There is also aftermarket cases, plates, and controllers which add programability. No, it doesn't have backlighting, but it's a solid base to build what amounts to a completely custom keyboard, without the hassle or risk. Burnt up the controller, broke the case or pcb? You can probably find a used one for a couple bucks. It may take some effort, some parts are in high demand, but at least they exist, try that on a Korean custom that had a limited production run intended for another country.
75% - Vortex Race
I loved the looks of the Limited edition white, however the quality was severely lacking, especially for the price I paid for it. Newer ones are better, and Vortex does offer alternative keycaps, but there may be better options.
65-70% - MagicForce/Qisan
It's basically a Leopold with standard caps at a severely discounted price. Well made other than the stabs being a bit noisy.. If you like blues get it with Outemu Blues and enjoy it for probably 1/3rd the price of anything really comparable.
60% - Only one I have even seen is my GH60 which I have yet to build. It too was an impulse buy.
40% - Not even really interested in them, too many compromises in my opinion.
Laptop - Lenovo Thinkpad, while you can argue over which generation is best, they are almost always better than anything else on the market. Older Apple are pretty good, but some are a bit shallow which is something I never expected to say about a keyboard, my Air is not that great to type on for this reason (on top of the fact that it's very low and flat).
Semi-honorable mention - Surface keyboard, the keys feels better than I ever would have expected and the Alcantara leather feels nice... When new. Alcantara is known for being horrible to clean and it will absorb oils and become a mess.