I have both, and I have the PM too. I started with the PM, didn’t like it as an agenda as found it difficult to write in. (I now use my PMs as notebooks for making lists.) I then graduated to the MM which I really love because it’s easy to carry around, but if you have the capacity to carry a GM I’d recommend that. It’s my favourite of the three but I mostly use it as a desk agenda because of its size.