What do you call someone who reads a Web site that’s primarily content-based? 読者 doesn’t seem right.
I’ve seen 利用者 used a lot, but that seems more specific to Web site services as opposed to, say, an online magazine.
If you mean a website like Unseen Japan which posts news and articles then 読者 is perfectly fine. ユーザー is always an option too lol Another word with similar meaning that comes to mind is 訪問者