Defently the ASUS R9 290 DirectCUIIOC, It's as fast as the GTX780, at a lower price. The ASUS cooler is amazing, i have it myself and it's pretty quiet. You'll need to go for the Powercolor version if you don't have an extra £5.
A couple of UK site have the R9 290 (not the 290X sadly) at just under £300, here's one now!: http://www.aria.co.uk/SuperSpecials/Other+products/Powe...
Keep an eye out at: Scan, Overclockers, Aria, Novatech, Dabs, Ebuyer, Pixmanina, CCL, Newegg (In the UK...YAAAAYYYY!), and Maplins...amongst others.
Be warned, some of these cards are very large and the R9 290 is well known as a compact room heater, make sure the case has enough space/fans to cope.
dual gtx titans anyone
i myself am going for the r9 280x for future value,future textures requirement,useability
in short better FUTURE fps
go with it or if you can stretch your budget try the 4gb gtx 770 or r9 290