Which is better for keeping the string in the middle and away from the sides?

The KonKave Bearing, or the Center Trac Bearing?

Thanks for the help!

Keeping it DEAD center, the KK would be better, but the Center Trac is good if you want all the advances of a flat bearing, but to keep the string away from the sides.

both but centertrac cause it keeps all strings to the center unlike the kk witch only keeps one