Tell your brother he is blasphemous and I will not stand for it!
Rule of thumb,
All cars break (VW's more than others).
Everything, and I mean everything, will boil down to maintenance when looking for used.
There are few early Foci that have had proper suspension repairs done, bushings, tie-rods, ball joints, bearings. Expect to repair them or ware tires fast and uneven. (apparently cutting a tires life in half is cheaper than fixing problems)
With the later ones, you will have the same suspension issues. The difference will be the age of the rubber. But miles can quickly take up the gap as well as geography.
Engine wise, both the duratec and zetec are reliable. It's the parts around them that give issue. If people listen and use Motorcraft replacement parts, they replace them less often and have fewer problems (this has been proven over and over, alternators).
Replacement parts are about the same for both engines.
I guess the duratec is better in that it is chain driven vs the zetec's belt. Less maintenance required,,, which people take to mean no maintenance. The guides do ware and should at minimum be checked near 100,000 miles, no one does.
If it were me, just look for a well maintained, clean, rust free car and call that enough.
Don't "think outside the box".
There is no box.
Do it correct, or do it twice.