Just bought a mechanical keyboard, the Redragon K551 with blue switches.
I've only had it for a few days, but it seems to work well so far.

Now for the downsides:

* None of the product pages say which key is replaced with FN. In this case, it's right Windows.
* The manual is a PDF with no text layer.
The only way to know what theFN key does is to hit it with every key.