Byakugan

A person with the Byakugan has a nearly 360 degree field of vision except for a small blind spot behind the first thoracic vertebra (near the back of the neck), which is its only known weakness. Byakugan users can detect anything around them within a 50-meter radius making them close-range combat experts. The Byakugan also gives the user the ability to see through basically any matter over extremely long distances. This seems to be a combination of x-ray and thermographic vision, note objects can be difficult to see if their temperature is the same as the objects around them.

Sharingan

The Sharingan's first and most well known ability is to memorize any technique that it witnesses. It can memorize anything with perfect accuracy, allowing the user to use the techniques as his own. In order to reproduce the copied menuveur however, one must have the necessary skill or ability to perform them. Additionally, Sharingan users cannot summon a creature that they have not made a contract with.
The Sharingan also grants the user incredible clarity of perception, allowing them to track fast-moving objects with great clarity and even predict the subsequent movements of those objects. The ability to track and predict movement is largely based on individual skill, as unskilled users have much more trouble tracking fast-moving objects.

I would personally enjoy the Sharingan, it's better to have with one-on-one fights so you can see punches coming right at you. Things along those lines.

Info provided by Wikipedia.

sharingan cuz ithink it's more useful^^

Feel free to take this here:
Sharingan vs Byakugan?