Here is a version guide, to tell which version it is.
http://207.99.34.129/versions.php
older version is always better, well to a point. There is a difference in dvd drives, but those are pretty random.
Version 1.0 to 1.3 have the same modchip, just installed differently (X-ecuter 2.2 Lit is the chip). It costs about 35USD, and for $15 more you can get a no-solder version if u cannot solder.
The X-ecuter 3 is comming out soon, which will work on a v1.4 and v1.5 as well as 1-1.3. So if you don't mind a wait, then it really doesn't matter which box you get. But, i highly recommend trying to get one of the first 3 versions for easement and the best price.