Old IBM mechanical keyboards are really nice to type on, but they lack a Windows key.
Can you buy one standalone? I imagine it having a USB cable and a single button.
Consider using Autohotkey to remap one of your Ctrl or Alt keys to simulate the Win key. Alternatively, you you can press Ctrl+Esc for the same functionality.
You can also get a custom single switch keyboard and program that to be the Windows key.
Select a key that you absolutely will not miss. Lets take the 'Scroll Lock' key ('Rollen' in Germany).
I have never used that and probably never will.
In Windows it is possible to remap all keys with the registry, so the goal is to remap 'Scroll Lock' to 'Windows (left)'.
You can do that with the program sharpkeys. The easiest way to configure the program is to use a standard keyboard (with Windows key), so you can press the keys instead of searching them in the list.
Once you download and start sharpkeys click on 'Add'.
On the new window you have to select 'Type key' (1) and press the 'Lock Screen' key. Then select 'Type key' (2) and press 'Windows (left)'.
Or you can select them from the list:
Accept with 'Ok' and press 'Write to Registry'. Then restart your OS.
Now you can insert every Windows key combination by pressing 'Scroll Lock' + , 'Scroll Lock' + 'e' opens the Explorer for example.
There are buckling spring keyboards, with a full 101 or 104 keyset. After looking at trying to get a good newer "Model M" I ended up here http://www.pckeyboard.com/ trying to select a perfect choice for me, that came in a buckling spring model. I am using the "spacesaver" now.
You could say some of the feel of the old style is making a return, so checking out other options like Duckey , Daskeyboard, Cherry, enduropro, and many others before picking one would be a good idea. Even sites discussing them is "big" Geekboards
A simple search at google for "mechanical keyboard" and restricting the search to "past year" will get lots of info.
So you can have your cake , with frosting, it will just take a fair ammount of research, to get the perfect one for you.