I'd have to say that some of the long time members of GameFAQs have the most posts. Post count isn't really kept track of mostly because there's too many to track. Every single day the popular boards get half of the total posts on the board deleted so you have what's called "active posts". I've seen screenshots of people with thousands of active posts. That means that in over a week/month's time they have posted 5-6 thousand total posts. Over several years, counting off time, vacations and lazy days... they have made well over several hundred thousand posts. GameFAQs posters>>>>>>> everyone else
i saw someone at a forum i made with over 20k, mostly spam though and they probably ended up geting into the ACP and changing their post count lol