Currently the primary source that I find the most trustworthy is Mangadex as they:
provide author/creator links to purchase their content directly on the manga/manhwa/comic page.
have been around for several years now.
have no ads and are funded by users, (their self-ads on April 1st are pretty great tbh)
provide frequent and timely updates on downtime and repairs (their means of communication could be better as they currently use Discord instead of Matrix or SimpleX)
Not sure tbh.
Currently the primary source that I find the most trustworthy is Mangadex as they: