As others have said, card specs are generally the same (or at least in the same ball park) in a particular model. The main differences are the cooling solution and any other bells and whistles a manufacturer will add on.
I generally put a lot of stock in user reviews for most anything I buy these days. A lot of them are pretty honest and while there are some that are blatantly "paid for" those are not too hard to spot. Another helpful resource, for computer parts anyway, are websites that let you compare all the specs side by side. NewEgg.com is my go-to for that. i am not sure if that site is an option for those in Europe like Amazon is, and the prices are in US Dollars, but specs are universal.
I took the liberty of putting both of Uni's linked cards and also an EVGA model in the same price range on NewEgg's compare feature. It looks like the Zotac and the EVGA are dead on with each other while the Gigabyte has slightly better clock speeds. Also the Gigabyte has different display connections which may be something to consider.
Then there are the bells and whistles. Shop informed I always say.
And wait for Black Friday/Cyber Monday!
Edit - Switching NewEgg.com over to British Pounds shows prices a bit better than Amazon, even with the VAT added (however that works). Shipping rates and times with Customs involved may prove bothersome though. On the other hand I get stuff shipped direct from China here in the US and sometimes it arrives faster than Amazon super saver shipping. Go figure.
https://www.newegg.com/Product/Productcompare.aspx?CompareItemList=48%7C14%2D125%2D901%5E14%2D125%2D901%2C14%2D500%2D402%5E14%2D500%2D402%2C14%2D487%2D260%5E14%2D487%2D260