If you want to create web apps with an editor, I’d recommend PlayCanvas over Unity. Recently they also did great upgrades to their free plan, so I recommend checking it out.
With that said, one big advantage Unity has over all other options is their very popular, huge ecosystem. If you’re willing to spend some money, you will probably find 90%+ of assets you need in their store, getting rid of a lot of workload and saving you time. It integrates very well into their editor.
PlayCanvas also has a store, but it’s not very big.
Out of these, three.js will probably require most amount of work, since it’s not a game engine. There will be LOTS of stuff you will need to do yourself and potentailly rely on a lot of 3rd party plugins. Community is pretty great and open though and you will have most flexibility.