RenPy is free and gives a bunch of flexibility to do stuff in Python. Last I checked, it couldn't export to web, so you needed to make executables for Windows and Mac which people download.
TyranoBuilder supposedly can output to HTML5 and has live2d support. I remember people complaining it was limited relative to other stuff (like RenPy). I think I remember some of the more advanced documentation and community stuff being in Japanese. It also uses a really GUI-driven development approach (kind of like RPG maker) instead of just letting you code, which can be a good or bad thing, depending.
There're some other Javascript VN engines (js-vine, monogatari) as well, but I don't remember seeing any that seemed really feature rich.
