WebCME which has a lot of features, notably a large library of molecules but is quite painful to use. This is because it's developers have chosen a system of 'select two atoms, add bond, deselect them, select another two atoms, add bond, oh wrong one, delete bond, add correct bond...' for drawing.
The ChemDoodle web components on the other hand have a totally minimalistic, yet powerful UI. Atoms are drawn by mouseclick, bonds drawn by mouse drag. Atom types can be changed via keyboard, bond types by mouseclick and delete is done by the Backspace or Delete key.
Unfortunately none of the three works on mobile browsers. Either they don't work at all or only by half.
In contrast, the jsMolEditor does work even in Android WebViews, but seems to be not under development anymore. I suspect that it was abandoned in favour of JsDraw.