The Accord and Camry are good cars, no question, but you’re going to pay a lot more both in initial purchase of a used one and on any repairs. The Ford Taurus, especially the later ones, have proven to be very reliable cars with much cheaper parts and much simpler repairs. The Ford Taurus you can buy for a given amount of money is going to be much more reliable than the Accord or Camry you buy for the same amount.
Of course, it all comes down to condition-- I think this trade the dealer is proposing sounds like a suspiciously good deal. Definitely learn your lesson and get the thing checked out before you consider making the trade.