Which of these sub no dates?

[PeterT]

Hi,
Been out for a bit of Rolex therapy with my son who is considering buying a Sub no date.
We came across a shop with a brand new Z serial non COSC Sub no date (2 lines of writing on the dial and the V serial COSC version with 4 lines of writing on the dial.
Both were exactly the same price with no discount possible. I see what people say about the cleaner look of the older model.
However, at another dealer I can get 10% discount on the COSC V serial version but they cannot get hold of the non COSC version.
So my question is:
Which Sub no date, non COSC version, Z serial at full price or COSC version, V serial with 10% discount?
In the UK that means a difference of £338.

Peter