In PlayCanvas you have to code actually. There is visual editor though. But no visual programming.
Babylon is actually under Microsoft.
Unity is no good for WebGL, and seems like not doing much to be so. It is the only from list using emscripten approach, which is not yet proven to be commercially viable.
I’ve found that usually evaluation of use or not is done by those criteria:
1. If project is alive and in active development?
2. Is it company or community managing project, if there is organisation providing support or is it community and driven by open source, or mixture of both.
3. Is it artists/game designers friendly — some visual editing tool.
4. Does it have visual coding abilities. Many decent developers ignore this point.
5. Showcase of technology in existing projects.
6. Is it mobile friendly? It is surprising how many webgl engines are ignoring mobile platform.