Currently I use Bookwalker. Things like light novels allow max 50 highlights, while manga can’t be highlighted at all (only bookmarking pages).
I plan to highlight vocabularies and phrases as I go, and no need to clear highlights. Not necessarily that I would study my highlights intensively, on the same day (or never at all), either.
I can’t get Kindle to work at all, while Honto and Booklive probably work. I haven’t looked into Kobo, which I can indeed install.
This is still not including very long articles I found elsewhere, and just copy in.
I expect to read on Android tablet and smartphone, and the page can be flipped (rather than a long downward scroll). So, sync is a plus. (It’s very unlikely that I would use a laptop to read extensively.)