mk6 Escort, is the 1.4 engine, or 1.6 better?

1.6 is the better engine, smoother, quicker and is much better on fuel

A 1.4 in good condition is not that that bad, I had to go up the hill out of Alderley Edge every morning, it a third gear 30mph hill about 1 mile long, engine runs perfect, you just don't go over 30 mph, but then again it a 30mph zone !
And of course the Tax and Insurance is less and when you want you can always pop in a Zetec 1600 or 2000 !

1400 in the mk4 Escort Orion is perfectly acceptable, I used to run an Orion Equipe and it used to do quite well. The extra weight of the MK6 blunts performance though.

The carb engine in the mk4s are good and the later multipoint injection is good too, the one to avoid is the single point injection

Which generation of Escort are you going for?

After driving a few Mk5 and Mk6s (a 1994 1.6 16v, 1993 1.4 CFI and a 1997 1.4 PTE engine), I would say that the 1.4s are not too bad if they are well serviced. Unfortunately the CVH derived engines do not take a lack of servicing well, which many will have fallen victim to.

When I drove my grandad's 1.6 16v around, it was a little pokier than the 1.4 but it was also better on fuel IMO. Cambelt changes only need to be done half as much on the Zetec as they do on the CVHs (which are known for having short belt intervals (disregard that information at your peril).

If you are going for a MkIV I would simply go for the best example you can find. Whilst a well setup 1.6 will be superior to a 1.4, a knackered distributor and a neglected engine will feel rubbish, regardless of which engine you go for.