Hey there! As sort of a fun project, I've decided to take on the task of making a game engine from scratch. I want my engine to have good AI support for simulation-type games and systems for fun, fast-paced experiences.

However, I want to ensure that the engine suits a broad user base and see what others think. What would you personally enjoy in a game engine?

For a 3d game engine, I'd want better level design tools.

I would like for a game engine to be able to have a lot of functions and easy and fast ways to create things like physics, collision, platformer module, shooting, steering, etc. that are very intuitive, and lots of templates. But within those very easy templates you always have the option to set advanced parameters and organize everything yourself.
So it allows for very fast game creation, and also the option to perfect and customize your game if you dive deeper.
That's what I would consider a great game engine.

I want the engine to be able to save the game at any time while playing and later load that game exactly, down to the position in the background music.  One of my biggest frustrations with Godot is that it doesn't provide anything like that.

For me, I want something like game maker studio, but with 3d and 2d game support, no drag and drop but code but with a lot of premade functions for common game problems and genres, automated memory management, being able to use zips as resource packs (mount, read, write etc), but no unnecessary components like sprite editors or draw programs (there are better 3rd party apps, I'd rather have the ide focus on easier coding for beginners). Lots of tutorials and templates. Keeping the core of something like GMS, sprites, objects, textures/backgrounds/graphics, sounds/music, rooms with layers, model and animation support (fbx, obj). It has to look nice and be performant. It doesn't have to be an unreal or unity killer. Maybe use a suite of preexisting apps--tiled for various components but optimized to work together