Prepare yourselves for a bunch of opinions!
1: Galleon Galaxy - I really LOVED Galleon Galaxy. Fantastic level design, a useful transformation and perfect level size.
2: Tribalstack Tropics - I liked Tribastack Tropics because of the great climbable monuments and fun challenges. It's also a great starting world.
3: Moodymaze Marsh - Moodymaze Marsh was good, and it felt easier to navigate. (More BK like maybe.) It didn't look that visually great though.
4: Glitterglaze Glacier - A great world, but it's pretty big, and a little hard to navigate. Locating the snowpiles with the truck was especially difficult.
5: Capital Cashino - Capital Cashino had some really great things about it, and stood out in a nice way. I did find locating some of the coins difficult though, and I also had a problem navigating the place.
Overall, I loved all the levels, but some were better than others. There wasn't a single one that I hated or didn't find interesting and fun to explore.