Cooler choice has a lot do with how one intends to sparge. Batch sparging is mash tun geometry agnostic. Many brewers attempt to continuous sparge in a rectangular tun with a slotted pipe or tubular mesh mash filter and write the process off as being no more efficient than batch sparging. Continuous sparging (a.k.a. fly sparge) is mash tun geometry and mash filter sensitive. A mash tun that will be used for continuous sparging should be cylindrical in geometry. It should also have a proper false bottom with 16 to 18 percent open space that is evenly distributed across the entire surface. With the proper pH and technique, it is not hard to achieve efficiencies that are very difficult to achieve with batch sparging (I obtained 35 points per pound with my last batch, which is an efficiency of 95%).
With that said, many brewers are very happy with the results that they get with batch sparging. Only you and your brewing partner can determine if you are willing to take on continuous sparging. I have been continuous sparging since since I started brewing all-grain beer in 1993. It's second nature to me now. However, I do remember getting less than stellar results at first. If I started today, I would probably opt for batch sparging.