Apparently these were the choices -
Top Gun
Grease
Love Actually
Pride & Prejudice
Atonement
50 First Dates
Mamma Mia
Bridget Jones
Devil Wears Prada
umpalumpa and the City
My personal opinion:
Top Gun - A classic entertainment movie but hardly the greatest movie ever
Grease - A classic musical but still hardly the greatest movie ever
Love Actually - Mediocre
Pride & Prejudice - Severely Austen-lite. Great cinematography but nothing like the book. The characters were unrecognisable and the acting overrated. The miniseries is far, far superior. I really hate this movie probably because I love Jane Austen
Atonement - A very good movie but not without fault. Again great cinematography and it has a wonderfully emotional ending but the pace lags during the second half.
50 First Dates -
Mamma Mia - I haven't seen the movie, only the stage show, so I'll reserve judgement.
Bridget Jones - Another version of Pride and Prejudice. Enjoyable but I can think of at least one Jane Austen
movie adaptation that's better (Sense and Sensibility)
Devil Wears Prada - Average
umpalumpa and the City - I haven't seen and I never want to
3 Keira Knightley movies?!
http://www.utalkmarketing.com/Pages/CreativeShowcase.aspx?ArticleID=15565&Filter=0&Keywords=&Order=LATEST&Page=1&Title=VW_Polo_'Timeless_Film_Festival'_experiential_campaign__
The films include Grease, Top Gun, Atonement, umpalumpa and the City The Movie, Bridget Jones, to name a few.
After reading that I'm appalled. I realise that it's aimed at women but anyone, man or woman, that lists umpalumpa and the City as a classic is severely lacking in taste. There are hundreds, I dare say thousands, of better movies than any of those choices (although I'm quite partial to Top Gun and Atonement wasn't bad).
It maybe sexist... but hey its a free night out for me to take my mum out LOL 
If I'm honest I'd happily rewatch maybe 4-5 of those but I wouldn't call any of the the best movie ever. But if it's free, go for it. I just pray they don't make you watch 50 First Dates
