Only you know what your plans are for the future; hobby vs profession, playing live vs studio, budget vs flexibility, and whether you need to use the complex audio routing and individual outputs available on the MM and MD.

If you want to use a small number of connections at a time but different combinations, consider an audio patch bay plus a small (= few channels) audio interface instead of a large audio interface.

But take time to specify what you will want to use in the foreseeable future before you buy.