Late to the thread, I know, but just wanted to chime in with a +1 for the MX Keys. I just got mine as a replacement for my K811 that spilled a double espresso into.
It had served me well for many years, and having used Logitech gear for about 30 years at this point, I do trust them to make great products. (As a quick due diligence session, I found this thread before ordering though.)
The MX Keys is my first full-size keyboard in many years and I do love having the big arrow keys and a full keypad available again. So much faster, convenient and accurate for numeric input. I like the feel of the keys and it has a lot of nice features, with a number of programmable keys as well.
FYI, the keyboard does have support for both Mac and Windows layouts, which can be selected by hitting and HOLDING Fn-O (Mac/iOS) or Fn-P (Windows) for three seconds. I’m suspecting that you’d see some issues if the keyboard was accidentally switched to support the wrong OS. The modifier keys is one thing that is mapped differently on Mac vs Win.