I often recommend guided tours for the added value they offer, particularly being with someone local who explains the history and importance of what you're seeing AND for the transportation to and from the places you visit, especially if you don't want to drive in a foreign country.
I cannot stress enough how many places would be off limits if you don't rent a car... as well as those places you just woulnd't know to visit.
In my experience, I would say a whole day tour to Pisa and 2 other cities and lunch would be worth the 90€, and a cooking class that starts in Florence and also takes you into the countryside to a farm (where you might not go without your own car) is worth the cost.
I am sure the experience will be worth it!
As far as which one is better, I recommend you take a look at the reviews for the tour from past participants - and also check how large the group is, because my own personal preference is always to seek groups of 20 people or less where you get a bit more personal attention, where you can ask questions and have the chance to meet others like yourself traveling from across the world to Florence and Tuscany.
I've done larger groups but the feeling is sometimes of just being herded around, so I will pay extra for smaller groups ;-). But if budget is sometimes a constraint, even those larger group tours do have their advantages (cost less and you get to see what you wanted to see in a short time period).