I like rotorburn, get linked to threads here, and am friends with bikers who regularly buy and sell things on this board.
Recently I need to buy some second hand equipment and have heard that rotorburn is the best place for it.
The 5 post requirement means though that now instead of voluntarily commenting on threads, with my new account, I have to cherry pick something to post to meet the minimum requirements trading requirements so I can ride again. It's a bit of a pain, especially with the formatting of the requirements, linking to separate areas, being a mix of fonts and colors. Just not a very friendly experience for a brand new user.