Depends on the Yoyo. I would never put a KK into a FHZ or slim Yoyo but I would in a Genesis or the like.
its always personal preference
but when it comes to contests i like using Center tracks.
for overall play it all depends on the yoyo some yoyos such as the 1st Bvm’s i really prefer it with a Flat bearing as suicides seem to open alot larger in my opinion.