Shimano 105 hubs are fine (~630g per pair inc skewers) and there are some good mavic rims. Open pro perhaps if weight is an issue. It's double eyeleted so that a good start and ones I have worked with have all built well.
However do not dismiss the Miche RC2 hub (~565g inc skewers). Cartridge bearings while being same price as the 105 and lighter than ultegra hubs. I use these hubs laced to Rigida chrina's with sapim race spokes on my road bike. Not a light set of wheels (because of the rims, I was on a budget) but so far after 2k miles they have proved themselves.
Loosing weight at the hub is not a something to spend extra cash on but why go for the heavier hub option for same money?
I think a 32 hole openpro build with miche hubs and race/comp spokes is ~1885g for pair. With 105's you can add 60g to that weight. However these weights are sum of listed weigths. I have no accurate scales as weight for me is a secondary priority.
It is possible to reduce weight further, if that is the objective, by using thinner guage spokes at the front and NDS rear.
I comparison the Mavic Ksyrium Equipe is meant to be ~1800g in reality. Also an open pro rim is probably lighter than the Ksyrium rim.
If you have or find a good wheelbuilder, keep then in business and get a pair built.