I wonder why this wasn't a topic before, perhaps it was, but what ever.
Honestly, I love *almost* all the music in the KI games. You can trust me if you don't think that yourself, since I listen to soundtracks of games, and stuff like Two Steps From Hell, on a daily basis. But if I had to choose one of those tracks, it would be Marleybone theme or something from Grizzleheim. Also, the music in Pirate101 is great too, it's definitely worth playing that game too!
One thing I have to say is that I literally hate the music in Krokotopia, it of course has something to do with my hate towards the world and theme itself, but the tracks there aren't that good until you get to Well of Spirits and stuff.