Between the two, I almost always prefer the forward clicky, simply because I can pulse light off and on, and usually end up saving battery life in the process, where otherwise I might leave a reverse-clicky light running when it wasn't really needed, or be forced to hold the button partually depressed manually.
The only time that a reverse clicky is preferable IMHO is in the case of the Fenix lights where each successive click causes a mode-switch. In that case, true momentary use wouldn't really work anyway (as it would cause the light to switch levels).
There is another option however, that is simply to use a small, cheap, durable signal-level momentary switch, and use transistors controlled by a programmed circuit to switch the light off and on. This is the way the Photon Freedom works, and it gives the user the option to have the light on in momentary mode OR in standard mode, where the light can be clicked off and on. It also opens the door for features like click and hold for dimming.
Capacitivbe signal-level switches are smaller, and more durable than either forward or reverse clicky, and with the right interface (perhaps a twisty to go between momentary and standard) can offer better usability than either one.