Louis Jacobs writes:
"In Slabodka they taught: man is so great, how can he sin? In Navaradok they taught: man is so small, how dare he sin?"
I think if Rebbe Nachman would to have to chose one of the two Derechs, he would chose Slobadka. After all the Rebbe's works are all about how much Hashem loves you no matter what, finding your good points, and recognizing your inner greatness, or gadlus.