Honestly don't have a favorite.. The car I enjoyed driving the most in my life was a Cadilac we rented in the US.. also driving my dad's convertible Mercedez was fun. But wouldn't count either as my favorite.
This is my current car though and I love it
New, manual, Fiat Panda.
lol I love those hippy cars! Especially when they're painted funny.
Higher end, hands down, it would be the Mercedes-Benz CL 63 AMG:
I used to work for the local Mercedes-Benz distributor in my country and had the opportunity to see this one up close and even ride in it a couple of times and damn, it is one sexy thing. Definitely my favorite car.
Lower end I love the Toyota Camry and the Toyota Corolla:
The Camry and Corolla are incredibly solid cards, highly reliable for extended day to day use and very affordable too. They also look great.