I'd say in general the MTX-75(Manual gearbox) is more robust than the CD4E(Automatic), although it can have some issues such as syncros, and possibly the differential depending on miles and wear, etc. Both engines are quite durable and long lasting, the Duratec(v6) having some known issues such as the water pump.
These cars can be somewhat more maintenance intensive. Do some research and you'll be able to decide which model is right for you.
Personally, I'd reccomend getting an SVT, or an SE v6-manual. You'll have the most fun that way
