Chapter 5 is also one of the better chapters. I loved seeing the various Yoshi colors and walking around exploring. Kolorado is also golden in this chapter and always entertains me. Same thing in the other fifth chapters, as Flavio and Flint Cragley keep me laughing. Chapter 5 always involves exploring and explorers in every game!
Chapter 6 would have to be my second favorite though. I loved the atmosphere.