For me it's:
X1: very good
X2: amazing
X3: okay at best, disappointing following the other two
Origins: let us never speak of it again
The Wolverine: Good! What a twist!
First Class: My favourite
DofP: good, but let down by being depressing
Apocalypse: good, could've been better.

With the last three, I really needed them to establish a status quo. Choose an X-team and stick to it. Without that, I can't get attached to their characters.