Hi there anon! Well, I actually like both series you know, and I’ve liked the series at different periods. I was addicted to KnB back in 2012, and I’m currently addicted to Haikyuu right now. Although I’ve gotta admit, I like Haikyuu better than KnB. And Haikyuu’s possibly my biggest sports anime addiction ever, well, I can’t really compare it to my addiction to Slam Dunk since I was still an elementary school kid back then. XD

Anyway, back to the question. I like Haikyuu better than KnB coz I felt more attached to the characters way earlier than the ones in KnB. All of the characters in Haikyuu are way dorkier than the ones in KnB. And personally, I think that Kageyama and Hinata’s rivalry/partnership is better presented than Kuroko and Kagami’s… plus the latter pair  were never rivals anyway, lol. XD I couldn’t care less about Kagami, I adore Kuroko, and I also adore Kageyama and Hinata.

The part of the series that I like more than the other is that Haikyuu is more realistic, hands down. I admit, KnB was really interesting at first but still, as it progressed, the matches became more and more ridiculous, all of them relied on the “zone” as if it was the basketball version of Bankai or Super Saiyan, and man, I even laughed when I’ve read that there’s a second door for the zone! Moreover, I liked how Haikyuu emphasized a lot on practice and hard work.. and they don’t magically win all of their matches as well. Seriously, I’ve never seen a series with the main team losing so much before they succeed. I also like the fact that Furudate-sensei even tries to explain the sports mechanics to noobs like us in the manga itself. :)

Anyway, I hope that answered your question! *glomps*