I usually go foundationless.
When I do use foundation, I buy Dadant small cell, primarily because the store in Waverly is nearby.
I don't know if SC fndn has an affect on varroa, as i ave never used large cell, but in several years of beekeeping I've never treated for mites, and never had varroa problems.
A distant third is Mann Lake's PF series -- the frames' are too flexible for my liking, and it doesn't get drawn as quickly and easily as foundationless frames or wax foundation.