So, you want to make an adventure map? You want to rival Hypixel? ( Good luck with that one ) You want to create something that gets everybody saying "I want that!"? It's really not as simple as it looks. Let me give you some ideas.
The average adventure map takes about 4 hours to make and 1 hour to add details. Very few of these maps get on the 1 out of 100 list, due to the fact that most of these kinds of maps take about 30 minutes to play through. There are other kinds of maps too, like ones that go on and on and on but the structures and storyline is terrible. So the question is, quality or quantity? To tell the truth, most people told me they would prefer both. We would prefer long and good maps over long and boring or short and epic maps.
Now, to make a map considered good, you will need to ad some pizazz, but the main point is don't put in too much. You could add one or two talking command blocks, but don't have a hallway filled with them. That will be strenuous for the player, and most likely make them want to quit the map.
Another thing is, don't make the map too hard at the beginning. I've played through tons of maps where as soon as you start, you have to go through this really hard parkour or something, and it's pretty much torture. So you can make it challenging anywhere else, but don't make it hard in the beginning.
If you have any questions, you can do one of two things: 1, look up hypixel and download one of his maps, or 2, ask me.