A new 3D Mario game is definitely needed, but I've also very much enjoyed my play of the 2D games. My favorite, which is my favorite game of all time, would have to be Super Mario World. To me, no other 2D title in the franchise has had the diversity of levels, superior map screen, and amount of things to actually do. There were several different worlds spanning a huge map, where all worlds were connected in an intriguing way. That, and the Star levels added even more replay value to it. If the next Mario game is to be 2D, which is what it looks like will happen, I would love for it to be like Super Mario World. Really everything about that game was just perfect to me.