It depends on a few things. Either choose the E52687W or the E52690 since they are socket 2011, which will give you the best upgrade-ability in the future. The E5-2687W is quite a bit cheaper, is clocked 200Mhz faster than the E5-2690, but consumes more power. If power consumption and heat isn't a problem for you, then I'd choose the E5-2687W for better out-of-the-box performance.
The Intel® Xeon™ E5-2687w under a normal server work load would be the fastest of these processor since Turbo Boost is based on heat and number of cores being used that would limit how much of a boost each of these processors were able to recieve when under load. If you were just running a single threaded application then the Intel Xeon E5-2687w and Intel Xeon E5-2690 would have the same performance due to them reaching max turbo boost. http://ark.intel.com/compare/64596,64582