You will not notice the difference between 2ms and 5ms. Other factors produce much, much more lag than any 3ms bump for the response time; 3ms (or 1/300 of a second) is negligible. If I were you I'd look up reviews for more accurate information. Those numbers don't tell the whole story.
3ms for a pixel to drop its light is a HUGE amount of time. I'm not talking just because of the numbers the monitors report or from the theory here, I've seen the difference (I have an old 5ms LCD and 2x 2ms LCD LED) and the ghosting is noticeable when there's a big contrast and the Hz are capped (you can check it with slow motion movement and high contrast videos).
Most 2ms have a setting to use the regular clock for the pixels powering so they last longer; obviously you have to set the response time to "fastest" or in my case "ultra fast" in the monitor itself.
My monitors are 22" 1080p 2ms Viewsonics: VX2253MH.