General consensus is NeoBitz is great for Neo Geo and Jrock for everything else. (waiting more than 1 min in the chatroom would help you get a response :P)
Neo bitz is a great encoder...according to the ng.com population... I myself, as well as a few others have had problems with the component side of it....evidently it depends on the revision of board you have. If you do go Neo bitz, make sure you ask for a POT upgrade, as the resistors that come on the board do NOT work with all consoles...