Chianti/San Gimignano or Siena/Montepulciano

Where are you staying and are you renting a car?

Hello! If you have just one day and "land" in Florence, it might be a good idea to go to the chianti area (eg: Radda in Chianti, Gaiole in Chianti). You can do it with bus, but having just one day it might be better to hire a car.

If you are traveling from Florence, check into taking a tour to a winery in Chianti that leaves from there. The recommendation is really dependent on where you are coming from and where you are going. It also depends on whether you'll be using public transportation or driving. I certainly wouldn't rent a car for one day.

From your other post, it sounds like you'll be visiting Tuscan wine country from your base in Florence. Neither of the 2-town options you suggest are efficient by public transportation. Chianti and San Gimignano are in different directions from Florence and Montepulciano is a fair distance away. If your objective is to tour the Tuscan countryside with minimal wine tasting, renting a car for the day would be your best option. In that case, I suggest Chianti and San Gimignano as they're closer to Florence. If you want to sample wines at wineries, then I suggest you book a tour and avoid driving altogether (legal limits are low).

Choose Chianti including Siena. Visit the villages and towns on historic SR 222. San Gimignano is to the west of Chianti. Very crowded with bus tours at certain times of day though worthwhile to see. Rent a car for the day.