I don't have statistics, but anecdotal stories suggest that reverse clickies are generally more reliable than forward clickies at the same price point, and perhaps even at considerably higher price points. I think the reverses have fewer internal parts, making them more robust.
For the record, when my forward clickies broke on me, they went out period, no light when half pressed, nothing at all...
There are highly reliable forward clickies such as industrial switches, but they tend to be just a little too big, or too expensive, or not have enough current capacity to be suitable for flashlights.