I would take a new Golf in a heartbeat. This generation has been quite reliable and the car drives beautifully. The interior is superb and the diesel makes stump-puller torque. The car carries a certain amount of cachet, too.
Finally, should your love affair with your car wane in a few years, a well maintained Golf TDi will command a good resale vallue.
Edit: I would not buy a used diesel under any circumstances. The Golf is less money than the Jetta and is, in my opinion, a better car.