Can you rent a car at the Florence airport and if so what one do you suggest
Yes you can rent at the airport. Be aware that you won't want a car while in Florence, so rent a car only when you leave Florence.
I generally use a consolidator:
www.autoeurope.com
www.kemwel.com
They are now part of the same corporate umbrella.
They work primarily with Europcar, Hertz, Avis-Budget, which are the largest operators in Italy.
You can also pick up the car at a city location, if you are staying in Florence a few days first. Picking up at the airport costs more because of additional airport fees.
I rented thru AutoEurope and got at Hertz car at their Sansovino location--2 miles from the train station. I caught a taxi over there. They gave me instructions to the motorway going south without getting near any ZTL's.
Any car rental at airports (worldwide) will often come with extra tariffs and taxes that are quite substantial.
You can turn a car in at airports without additional charges, however.
Check the rates at both airport and city locations. On a recent trip to Sardinia, my Europcar rental through AutoEurope was €40 cheaper at Càgliari airport than in town. Might not apply to most rentals, but double check!
The car rental area at the airport is at present occupied by a construction site (they will need a few years) so rentals were moved to a free area on the other side of the main highway. There is a bus shuttle every 20 minutes to rental park area (too distant to walk).
http://www.aeroporto.firenze.it/it/i-passeggeri/trasporti/autonoleggi.html