The Taurus, mostly because of the baby. The Golf really isn’t a high-quality car. In Europe it’s almost always the best-selling car and has been for years. That sounds like a good thing, but what it tells you is that the Golf is designed to be an ordinary family car, not something special. The materials used are ordinary and its reliability is very average. You’re right that it will start needing more expensive repairs as the miles and years increase. That’s true of all cars, but VWs seem prone to more costly repairs than most makes. The parts are not cheap and the repairs are often complex.
The Taurus is to America what the Golf is to Europe, an ordinary mid-price family car. Age matters as well as mileage, so don’t ignore that the Ford is older. A car of that age with that few miles has probably been used mainly for short trips, which are hard on a car. That same mileage run up by a commuter in three or four years would be much easier on the car. Also, has the car been sitting unused for some time? That’s also rough on a car. I’d have the Taurus checked out thoroughly by a mechanic. If they haven’t been replaced recently, have the fluids drained and replaced (oil and transmission fluid at least). I don’t know whether this car has a timing belt (most cars of that era do), but if it does it is probably due to be changed, not because of mileage, but because of time. Generally they specify a maximum mileage and a maximum time. The mileage is usually around 100,000, and always more than 52,000, but 16 years is too long. Check the age of the tires, too. They may well need replacing even if they don’t look worn out.
As you can see, the Taurus has a lot of potential costs. If it has been used continuously and the maintenance schedule adhered to, it could be a great car. If it has been unused for years or seldom used and the maintenance has been neglected, you may have to put some money into getting it back to proper running condition. The Golf you know more about, but you’re right that it may need expensive repairs not too far in the future. I’d take the Taurus to a mechanic and find out what it needs. If not too much, I’d keep it. They’re both oldish cars, but it’s a lot better family car with lower mileage. With a little luck you could get quite a few more years out of it.