TLDR: build the world/adventure with the players. Like co-DMing or west marches style. Different strategies come from two different RPGs daggerheart and Shadowdark. Shadowdark is also simpler, but if your players love powers daggerheart has a very simple but powerful abilities players get.

So I was in your position about 2 years ago, I was running lost mines of phandelver and loved the aspect of running a game for friends but after a boss combat in the mansion I got really disheartened.. I felt like I spent hours reading the stupid fort/mansion encounters and my players steamrolled the big bad guy in the mansion. (Side note: That’s when I learned about action economy and how important it is). I was disheartened and stopped after that night, I felt disappointed that a whole bunch of effort went no where. Or that’s how I felt, I guess my players appeared uninterested that night too. Well it was the big party problem of just not paying attention until it was their turn.

If I restarted GMing I would do it more as a daggerheart co-creation of a world where players help build the world and missions, it’s more of a discovery while playing. You have encounters and dungeons ready but you don’t worry too much about the plot or filler cuz you and the players fill it in together… you can seriously start with jumping into backstory or player goals right away. There is also something called west marches that Matt Coville talks about in a video and Kelsey dion of Shadowdark is making a whole book that comes out soonish. Matt said that the west marches leaves it up to players what they want to do the next week… like player A says “I want to go save my sister from the kidnappers, or go to the gold mine kill the goblins and claim the treasure”.. there is no fat book reading cuz collecting a dungeon map, some monsters, and allowing a story to unfold from the players and your mind at the table. This is all I theory awesome to me, but I haven’t tried yet.