I don't think that is a fair question to ask! The reason i say that is because the Byakugan has got almost no spot light since neji fought Naruto and Kidomaru. The Sharingan is used so much that i think poeple don't actually know how the Byakugan actually works and the full extent of its abilities.
All poeple have see for the most part is nothing but the Sharingan, and we've never actually seen a Byakugan vs Sharingan fight.
People say that the Sharingan can predict movement of the user, this is correct it can, but the Byakugan can see in an 360 degree vision which allows the user to see and react to the attack almost instantly. These are the words ofKkidoumaru. The Byakugan also has far better insight then the Sharingan(stated by Kakashi), which if used correctly will allow the Byakugan user to effectively predict what an opponent will do. As effective as Sharingan, probably not.
Both can see the chakra within the Body, Byakugan Also excels in this because not only can they see the chakra, but they can also see the chakra network system. And with proper discipline, the Byakugan can watch and see where the chakra is being molded and effectively counter where, and how powerful the attack will be.
Sharingan main advantage, is its ability to copy non kekkai genkai jutsu and use it for themselves. This is an amazing ability, but like all humans, Chakra is limited and can make copying useless if you don't have the Chakra to support it. (Kakashi is the perfect example)
Sharingan can be countered, but two different skilled opponents, but is not possible with a Byakugan User as they have 360 degree vision. Oh and let us not forget that the Byakugan can also see miles ahead if necessary to do some recon.
I don't think its fair to say Sharingan is best because its my favourite.
No, it all depends on skill of the tool used by the shinobi. Byakugan and Sharingan, both kick ass.
But in my personal opinion Byakugan is better then 3 Tomoe Sharigan!