The Ikemen version is probably a little better if your looking for new features. It supports tag mode which is a big deal to me since I made my characters inspired by Capcom's VS series. There are other cool things the engine can do for example, Arcade mode allows for multiple stages for 1 character. So all those alternate stages I made for Ryu will now have a purpose. Ikemen Go also supports online play, is open source and still being updated. So it has a lot of advantages now that Mugen will unfortunately never have.