Naruto, as he did his own series, turned Kyubi into shit...like, he made poor Kyubi come from a badass, to a lame Pokemon... The poor thing didn't deserve what the evil Naruto has done to him...
Kurama. Kyuubi made it seem like no one could really beat naruto cuz all he had to do was get mad. Now more threats that are way out of kuramas hand are in play
I like them both, since they're 2 sides of the same coin . It was nice seeing the Kyuubi's rampages, as we later found out how it symbolised his misanthropy towards humans. However, it was also good seeing Kurama show his "intelligent and kinder" self interact with Naruto, and showcased his true personality which was brought out by Naruto. The two dovetailed each other.
Both. Kyuubi was was mysterious, wicked and had this, as you've said, classic, malevolent presence. But, Kurama was wise, caring and so very funny! I loved the light-hearted interactions where he would poke fun at Naruto!