Which is the best language cross-platform kivy or html5 (ionic) ?

Answer 1

kivy python is quite powerfull, HTML is more universal.

Answer 2

If you plan to make website, Html as no alternative ^^

If you plan to make a Python program, Kivy will be more efficient than using Html ( meaning using web views extentions to... any GUI, even Kivy )

But, if you plan to make a mobile app', the mostly efficient way is to use Java ( on android, Swift on iOS ), as Python can be run in mobile, but it's heavier than necessary and slower than anything: not impossible, but not the best practice :P

Answer 3

Html5 Because every os contains a browser.

while kivy will work when you have installed Python.