i'm reading up on the differences between 360 and ps3 for eternal sonata on wikipedia and it's saying that the ps3 version has extra content and got overall slightly higher ratings. is there ANY reason to go with the 360 version?
Not unless you just absolutely love achievements. The PS3 version came out about a year later and was improved over the 360 version (including new characters & a few added story points- if I remember correctly). Still highly recommended game regardless of platform.