The towers of Bologna are much more famous and I think a bit bigger. But they are on a random modern intersection and surrounded by tall buildings that don't allow for much of a view.
San Gimignano has very similar towers and it has both more towers and better preserved ones. And you can even climb up the tallest one.
The whole old town is very impressive. As someone who has been to a fair share of medieval towns and castles, I think this one earns a 10.
