To me, the most important attributes is, is it fun to drive and does it put a smile on your face everytime you drive it. Power, handling, braking all fall under this attribute. If it doesn't have enough power and doesn't handle well it's not gonna give me that silly grin on my face. Everything else is secondary but still important. It has to look good (although I would trade some quirkyness for performance anyday i.e. WRX), be comfortable enough to drive everyday, and be reliable. It should also have some personal touches that reflect your taste like custom wheels, seats, ect. so the car is like an extension of you.