According to Samsung and other e-tailer, the specifications does state that the response of GTG is 2ms, 5ms probably refer to BTB (Black to Black, or On-Off-On).
If you're looking at fast response, you'll sacrifice colors, it'll be the same for all TN panels.
http://tinyurl.com/2bgdha3(Untrusted? Click this to see the actual URL >>
http://preview.tinyurl.com/2bgdha3 )
This is newegg's 27" monitor product sorted by ratings.
Asus ranked first... should you get Asus? Well, read the customer reviews before you decide on one.
Want great colors, you probably looking at IPS, which is not just expensive, but you sacrifice the response that you wanted.
One note, manufacturer specifications might not always correct, my 5ms 2333SW ran through a response rate test and guess what? 16ms as a result, so a 2ms might not be always the case for LCD panel. Good luck with your purchase.