What is your budget for the new card?
What are your full system specs?(CPU,RAM,etc.)
If you have to choose Zotac then go with the AMP! edition.Their's no point in getting the 4GB version unless your plannong on running Nvidia Surround.
I would suggest going for the MSI TwinFrozr GTX680.it's build quality and cooling is one of the best.The Zotac AMP! edition's cooler is also good but it actually makes it a triple slot card which can be difficult for SLI setups.The Twin Frozr is also cheaper.http://www.newegg.com/Product/Product.aspx?Item=N82E16814127672