Cash.
As a young lawyer I was introduced to the concept of "eff you" money. You save up enough cash so you can say "eff you!" to your law firm, clients or both.
Count me in for the Cash, and I agree with the legal preference for eff you money.
As a young lawyer, my eff you fund is currently insufficient even for Lady Noto's ring. Thereafter, downpayment on a house. Thereafter, a car. Thereafter, kids. Thereafter, chocolate. Definitely chocolate.
A fancy car would be a massive waste to me before the age of 40ish, and thereafter (the key word), I'd rather spend it on vacations.