Dual pivots have slightly more mech advantage and are easier to center and keep centered. But I have Dura-Ace single pivots from 1986 on one bike and Dura-Ace dual pivots on another and I can't tell the difference in braking power and I've never had problems centering either.
Dual pivot brakes are better hands down choice. Been riding for a lot of years and am in the range of 200#. Do a lot of mountain riding and double pivot brakes are real brakes not merely speed attenuators. For years I rode Mafac brakes which could be called double pivot brakes (old school). When I put a set of dual pivot brakes (campy) on my bike in 1991 I was amazed. I have always been on the large size for a rider and lived in mountainous regions...worst case testing. If you are less than 150# and ride mainly on the flats then it probably makes little difference...but. Good luck with your build.