I have the PM, MM and Desk Agenda. I use them all but really have my eye on GM for awhile.
I have used PM as a wallet, planner, coupon folder in the past. Love it so much got it in epi and mono.
MM have been using religiously for home planning, but wish had GM.
Desk agenda is least used, but I use it for journaling and planner in the past.
Hope that helps, you will love any of the sizes❤️