The 1.9’s in the older vans are generally the more reliable option and the same engine goes in so many things that parts are plentiful and anyone can fix them.
The 2.5’s are a little nicer to drive but have more trouble than the 1.9’s. A bit better after 08 as the camshafts are hardened from that point on. Means that servicing with the right oil is a must. They are harder on parts with the greater power especially drive shafts and exhaust manifolds.
The newer 2.0’s don’t seem to make much difference to economy, I’ve had all types and get 40+mpg on a decent run 30mpg ish around town. They are newer so it’s harder to be sure what the problems will be with these with any certainty, 4 years just doesn’t give a broad enough history.
For me I’d probably be looking at the newer vans only as the residuals will be better.