Non-reverse clickies work best for me. This depends, of course, on how the clickie is made. If it is of high quality and not easily turned on accidentally, then we're in business. If it's of low quality, that's an entirely different story.
As someone else mentioned, for the price of the high quality lights we're all buying (read: Surefire), clickies should work perfectly. The two clickies I have for my M3-CB are not as dependable as the twisty. Reason: The clickie tends not to work properly when tightened all the way down. Therefore to fix, I have to exert quite a bit of manual pressure on the clickie spring with my thumb, compressing it for a while so that the spring begins to "take a set" that is less tight. Then it begins to work as intended.