Welcome to the forum
Check the gearbox on the 2.5's .
Dual mass flywheels can be a pain on the 1.9 and 2.5. (check for clutch judder)
1.9's also have a cambelt so make sure thats changed or has been if over 60k. (think 60k is correct)
2.5 no cambelt.
1.9 has 2 different powers, 85bhp and 104bhp
2.5 has 2 different powers, 130bhp and a 174bhp.
Both are good engine IMO but prefer the 1.9 a tad more due to parts be cheaper (secondhand) and a bit more easy to work on than the 2.5. Saying that i have a 2.5 at the moment, But just always have a feeling that if something goes wrong it may cost more and be a bit more of a pain of a job to do.