Steelseries QCK+ or QCK Mass.
QCK+ is huge, but thin. The QCK Mass itself is also quite large, except it is smaller than the QCK+ but thicker. I am using the Steelseries QCK+ and I could not be happier with it
When I bought the QCK+, it is pretty cheap, I bought it for $25 or less. The QCK Mass, if I recall correctly, should be a little bit more expensive.
I'd
HIGHLY recommend getting a limited version of the QCK+ from here:
http://www.amazon.com/SteelSeries-Gaming-Mouse-Pad-Navi-Edition/dp/B005OCBZB2/ref=sr_1_3?ie=UTF8&qid=1378648392&sr=8-3&keywords=qck%2B
The limited edition QCK+'s are the ones with a gaming team design.
It is thicker than the normal QCK+, but still crazy large. My friend has it and I really regret not getting the Natus Vincere edition, since it is more thicker than the original QCK+.
The normal QCK+ is 2mm thick, whilst the QCK+ limited editions are 4mm thick.
If you do not like the Fnatic/Navi/etc design, then you can go for the QCK Mass, which is slightly smaller than the QCK+ but it should be more thick (6mm).
http://steelseries.com/products/surfaces/steelseries-qck-plus
http://steelseries.com/products/surfaces/steelseries-qck-mass
Though the QCK+ on Amazon is sold by a 3rd party and is insanely overpriced, so go for one of the QCK+ limited editions or a QCK Mass