The best gpu in this range is the 7870, so I would stick with that if you don't want to increase your budget.
Out of those options the gigabyte is the best, considering it's the lowest price and has the highest clock speed. That cooler is great if you have good cooling in your case, but if not you may want to opt for a blower style fan, like in the his iceq. As I do not live in the uk, it is difficult to suggest a video card, as prices and availability change.
Also, make sure your case can fit the video card. The his iceq 7870 is about 30 cm long, so don't buy a card that won't fit.