I am building a pc with Skylake and went with 16gb (2x8gb) Corsair Veangeance LPX 3000mhz CL15 kit [Skylake scales well with higher frequency; but for X99 2800mhz quad channel is the perfect choice, in my opinion] . It was a good deal when I bought it. If the frequency and the timings are the same(highest frequency and lowest timings work best) and you don't have RAM clearance issues (need low profile ram) I say go with whicever option is the cheapest at the moment (Corsair, G.Skill, Kingston make great RAM).