This is just for the sake of curiosity for anyone who's interested in responding.

I've always really enjoyed Jiobob (world 3), just something really pleasant and fun about it. But I've also taken quite a liking to 2-7 because it flows so well and 4-3 comes from a casual perspective of always liking this arrow based level. 5-3 has been and always will be "THAT" level to me but picking it up and thrashing it in a speed run feels so satisfying.

What are your opinions on this?

The bomb ones are harder for me for some reason when training but my favorite is 5-6. A speed run level built in whether you are speed running it or not, even though it's optional during the regular walk through.