Construct supports Javascript coding in addition to its block-based approach. Javascript is an industry-standard language used widely across browsers, servers a...
of course Construct is better on HTML5, GameMaker still has some major problems on HTML5, touch input still doesn't work well on mobile devices on HTML5 export!
In my opinion all engines have pros and cons, unity is powerful multiplatform engine, it can handles more than 100k instances easily using ecs, but when it comes to HTML5 it's terrible!