The top one is the most overclocked in the bunch. The bottom has a newer version of Open GL (4.2 versus 4.1) but has the lowest clock speed. If you use HDMI, then do you have a full-size or miniature HDMI input for your monitor and/or TV? These are the only details I can make out that have any considerable effect.
I don't have much experience in the field of computer gaming (console gaming is another subject), but I'd lean toward the top one myself if I had to decide among the 3. It's not only the fastest one of the 3, but it's also cheaper, a double bonus.