I have and love both, but the mini rectangular is much more practical because it fits a regular size phone and a few more small items.
My extra mini coco handle fits my little iPhone SE (which I bought specifically because I have so many mini bags), but I have to take my case off so I can get it out of the bag more easily.
I love Coco Handle. And this is gorgeous with light ghw. I agree that Mini can't hold much. I have the Small and it fits my needs. I also like the length when I wear it crossbody (5"3)