You're a foodie, the answer is clear, Bologna. The first time I visited...I ate two dinners in one night there.
How many more cathedrals, piazzas and statues can you see? Admittedly, after the first week of a trip, I'm tired of seeing churches, paintings and town plaza's. Italy is full of preserved history over a broad arc of time, BUT, when one mentions Italy, food is what's #1 and Bologna is the epicenter of many familiar foods.
The flip-side, you'll only be in Tuscany for 3-days, not sure where you're coming from and going but, with three days, and if you're there to explore and seek-out all of Tuscany, Siena is a beautiful town that rivaled Florence for centuries. Bologna is on the other side of the Apennines in Emilia-Romagna, a different region all together from Tuscany, perhaps saved for a different trip to explore, Parma, Ravenna, and Ferrera.