I would rather work on native applications in general. When thinking of ports under Haiku, my first objective would be to just get the software working, but it's often all about porting the dependencies. Efficiency is hard to achieve, and you wish you could just use the native kits and avoid a copious amount of work. I think therefore that applications with a graphical interface should use the Interface Kit, any media player should use the Media Kit, and so on. That said, I'm not sure of how simplistic this point of view is. I have no clear idea about how to add DVD playing support to Media Player, or how to implement media streaming (Media Kit? Network Kit?). Another thought was about native functionalities ports would miss out on, replicants for example. I'm pretty sure that replicants for the media player and transmission would be useful and even welcome in some cases.