Well, some popular manga websites include Viz Media and MangaFox. Viz Media offers officially licensed content, while MangaFox has a large collection but be aware of the legality of some uploads. It's always best to support official sources when possible.
Websites like KissManga and MangaFox are often used. They offer a large collection and are user-friendly. However, be aware of potential ads and the legality of some content.