Okay, waited to use the 28 a bit before replying, and quite a bit have I used it too.
Basically, it is as
@papertiger says. The 32 is a great work bag. It fits my IPad Pro 12.9” inside a pouch. And you can add a pair of heels or one of my Acne blanket (i.e. huge) scarves on top and quite a bit more. It looks very smart and professional, like a feminine and light version of a briefcase. Mine I see it as a winter season bag, but that may be the color and leather combination more than anything.
The 28 is much more versatile. I have actually been surprised just how versatile it is. It can very well function as a work bag. It fits my IPad Pro 11”. It does fit a pair of shoes. It does not really fit a blanket scarf, unless it is the only thing you carry, kind of using the bag for its original purpose

. Compared to say, the Kelly 28, it fits so much more due to its rectangle shape, symmetry and absence of flaps or any other fuss. Which I know it is stating the obvious but it is really remarkable. I also like it fits perfectly in the bike’s basket. In terms of looks, I also find it very versatile. It can be very prim and lady like (specially in the box), but it can also read preppy, and because of the simple lines it can also look quite modern and minimalist, depending of what else your are wearing. Thinking about it, apart from the typical work-lunch-shopping, I have worn it in many different situations (college alternative film festival, lawyers tea party, minimalist avant garde gallery opening, school function...) and it seems to adapt very well to whatever environment...
So I’d say, if you have to choose between one of the two I would go for the 28 for versatility, unless you are looking for a work bag and you carry lots of stuff.