Best Worlds in Super Mario World
Donut Plains is, in my opinion, the easy winner for worlds in this game. There's not a single thing I didn't like about this world! It's not even the first world (that's Yoshi's Island), but I feel like this is the perfect introduction to the game itself.
The map is big and riddled with secrets all over it, more so than even the following worlds! And the levels are classics! From the two ghost houses, the cape feather introduction, the top secret area, the music, the good auto-scroller, you name it. Easily my favorite world.
Forest worlds are always a banger in Mario. Unfortunately, this one isn't quite as good as the average forest level, but it's still good. I love the concept for this world. You need to find the secret exit in every level to proceed (except the Ghost House) if you want to get anywhere, or else you're stuck in a loop.
Unfortunately, the levels weren't that great. One of them is the worst underwater level in the game, one has a really annoying gimmick with bubbles, and one has a very ugly color palette that includes bright green and blue. That being said, the first level is awesome, and I love the Ghost House. So this is 4th place.
I have no idea why people say this world is so hard. Yeah, it requires you to be on your toes since it's the second-to-last standard world, but I never had any real trouble with it except for the Castle level.
Aside from that, this is definitely one of the most interesting worlds in the game and one of my favorites. The chocolate theme alone is pretty unique, and the levels did a good job incorporating the chocolate tileset. The levels are some of the best in the game.
The ghost house actually requires you to really use your wits to beat it. Choco Island 2's layout randomizes every time you play it based on your performance, and so on and so forth. How can this not be #2?
The Special Zone contains the hardest and most complex challenges in the game. For this reason, I can't put it under the top three. The levels here are some of the most brutal and fun ones in the game. Tubular is especially aggravating and difficult, despite it being pretty short. All other levels aren't that difficult, but they can still give you a hard time. So this one is #3 for me.
A generally decent and fun underground world, taking place inside of a mountain, Vanilla Mountain to be exact. Unfortunately, it is a bit of a letdown after the great Donut Plains, but nevertheless, I always have fun playing this world, even if the atmosphere isn't my jam.
All levels are decent to play, and it's especially interesting how you can basically beat this world in the first level by getting to the secret exit and thus you're already on the next world... well, the top bridge of Twin Bridges that is. Overall, a pretty good world!
This world is okay. Instead of being a lava world, this one is set in a valley, a cave under the sea, whose entrance is a sunken ghost ship. As a world, it's pretty okay. It's more bearable than Dark Land from Bros. 3 but also less interesting than it.
The levels are, for the most part, just boring underground caves that aren't interesting, unlike in Vanilla Dome where they're pretty good. But the final level makes up for that, containing one of the best final bosses ever.
Yoshi's Island is the first world in the game, but it doesn't have any of the qualities to make an amazing first world like Grass Land in Mario Bros. 3. Instead, it's rather small and insignificant, and none of the levels scream out to me like in Grass Land (except Level 1 and the Castle maybe).
It's just too easy, too forgettable to be any higher. Donut Plains was much better at feeling charming and memorable than this.
Of the standard seven worlds, Twin Bridges has got to be the worst one. Not that it's bad, but it's not great either. Twin Bridges is just too small and too insignificant to be any higher than this. It's literally just two bridges with a few athletic levels and that's it.
Ok, there is an underwater level too (the only good one in the game, Soda Lake), but the levels overall aren't very interesting. One of them is even an autoscroller. One interesting part is that the bottom bridge can be reached by completing Vanilla Dome normally, while the upper bridge requires you to reach the secret exit in Vanilla Dome 1. Other than that, not terribly great.
Star World is in last place for the simple fact that it's just not interesting. It consists of five different small levels where you can acquire one of the four different Yoshis, and you need to complete the levels through secret exits to travel between the normal overworld map quicker.
None of the levels are fascinating. They're just very short and don't serve much more of a purpose than being shortcuts. So, it's not bad, but of course, it's the worst.