The Logitech K810 is a good compact keyboard. It uses scissor-switch rubber-membrane keys, like Apple keyboards do, but unlike Apple keyboards, the keys are of standard size (.75 inches between the line through the center of one row and the line through the center of the next row -- same as almost every desktop keyboard since the keyboard on the original IBM PC but
different from Apple's keyboards) and they are slightly curved (spherical, to be exact, as opposed to cylindrical like most desktop keyboards or flat like Apple keyboards).
It is wireless, illuminated, light, only a few mm high and able to be picked up with one hand. (I value lightness and ability to be picked up with one hand highly; maybe I pick my keyboard up more than most people do.)
(Disclaimer: I do not actually own a K810, but compactness is not a requirement or a desire for me -- time spent moving my hand to and from the mouse is not something I seek to reduce. I did test drive a K810 for a couple of weeks and own similar Logitech keyboards (two K750s, which shares the Perfect Stroke system with the K810).)
I tried a mechanical keyboard (with Cherry Brown switches) and it was nice and all, but when you press a key, the feel of the Logitech keyboards with the Perfect Stroke system (the K750, K800, K810, wired Illuminated) is sufficiently close to the feel of the mechanical keyboards that the other advantages listed above -- plus the fact that the key tops are spherical rather than cylindrical -- put the Logitechs in the lead.
Note however that the keyboard I am recommending is more expensive than a mechanical keyboard when you account for the fact that the mechanical keyboard will last for about 10 times more key presses.