It's light. Compared to Unity which spends ages creating projects, compiling scripts, building, etc. Godot feels very snappy. Unity also generates about 350mb of placeholders every time you create a project, something I always held a grudge against because my drive isn't very big (500gb)

It's open-source. Obviously a big reason for a lot of people, it feels good not to have to worry about any licenses or a business suit CEO saying devs are idiots

It's more cohesive. It increasingly feels like you need a lot of extensions to get work done on Unity, and there are like 3 different systems to do one thing. In Godot everything feels more straightforward, and it's batteries-included so you have support for things like Tweens out of the box compared to Unity. Things are generally easier too like Autoloads compared to having to manually make singletons.

I love signals. Probably the most subjective thing, but for me, I think signals are great and a way better alternative than blindly calling functions on another object. Other engines may have it but usually they don't work very well.