My favorite keyboard remains the last generation Apple Keyboard (Model A1048):
It looks great, is very space efficient, is very quiet, and the layout is near-perfect (the location of the F13 key, which corresponds to Print Screen, being off is the only nag I have with it). Using it on a non-MacOS system requires a bit of key remapping, but that’s easily done, and afterward it will work fantastic on both Windows and Linux. My affinity for these keyboards, it seems, is only surpassed by my ability to repeatedly spill liquids on them that end up destroying them (I must’ve gone through at least 7 or 8 of these…)
A very close second would be its predecessor, the Apple Pro Keyboard (Model M7803):
It’s a bit bigger than its successor, but the layout is a bit more traditional, and the location of the two USB slots are better. Since I no longer have any A1048 keyboards to use, this is now my primary keyboard.
I’ve also used and owned plenty of others, including the old IBM Model M. They’re definitely good keyboards for typing, but just too loud for my tastes.