Cabas Mezzo!! It is a Classic bag I like the Totally for a "mom" bag as some members told me it resembles a diaper bag. Both cute but Mezzo is perfect! I wanted that one but I got the piano because I'm only 5'1 and didn't want a ginormous bag to hold lol.
I have both and LOVE both. The mezzo was one of my first shoulder bags I bought. It is my work horse of a bag. With that said, my mezzo is used...and abused!!! But well loved. The totally is an updated version, IMO. I love the side pockets and the pockets inside the bag can't be beat (which the mezzo lacks). I like the bottom of the totally better since it shows less wear. I think the mezzo must have a purse charm (at least mine must!!!), cause it tends to be slightly plain. All in all, both are great bags. I think the totally MM is a very comparable size to the mezzo, if that helps.
I have the Cabas Mezzo and a Totally MM. Although I love both purses, I really LOVE the Totally MM. It's actually a very soft/pliable purse and is quite roomy (bigger than a Cabas Piano).
The Mezzo is much more stiffer and larger but you have to be careful with the vachetta bottom. It's still a great bag, but I do tend to use the Totally MM more often. I actually had considered a Totally GM but decided it was too close in size to the Mezzo, so I bought the Totally MM. I used to own the Piano, but sold it as it was too small for me. The Totally MM is a nice size. Mezzo is taller and stiffer.
If I really had to choose between the Totally MM and Cabas Mezzo, I think I would go for the Totally MM.