As you are probably aware, Revos are 14/17/14 or 15/17/15 gauge and supercomps are 14/16/15. DT defines 14 gauge as 2.0mm in diameter, 15 as 1.8mm, 16 as 1.7, and 17 as 1.5mm.
The part of the spoke the most often breaks is the head (hub end.) Having a stouter gauge there will increase the longevity of your spokes. If you are using alloy nipples, 15 gauge at the threads is better than 14 gauge. This is because the weakness of alloy nipples is not the thread engagement with the spoke (they almost never strip out,) but rather the strength of the nipple when a spoke wrench is on it at high tension. At higher tensions (above 115kgf or 1150 Newtons) 14 gauge alloy nipples start to round off rather than turning on the spoke. 15 gauge nipples seem to be a little tougher due to the smaller hole drilled through them for the spoke and therefore more material contributing to the integrity of the nipple. The last reason is the super thin 17 gauge wire spokes twist very easily*. when you are trying to true you wheels the spokes just twist and twist and the nipple doesn't turn on the threads hardly at all, and not in any sort of predictable fashion. Thicker spokes resist this twisting much better and are much easier to true.
So, to sum up: 14g at the head is best because it is strongest, 15g at the nipple is better with alloy nipples, and 16 gauge is better than 17g in the middle because they don't twist as much when you are building/truing them.
*There is a tool called a Twist-Resist that was intended to prevent a spoke from twisting when you are truing wheels but it is a $30 piece of crap. It really has a hard time holding onto light gauge spokes which are the ones that twist the worst.
This is the most sensible thing that has ever been said on this forum. I agree with all of it, right down to the commas. Well put, Jer.