What Are The Differences Between Samsung Firmware Version For Countries In The Same Region?
I guess that they are optimized for a particular country for example they will use different wifi channels (you should find the best channel anyway for best speed) and for different mobile communication infrastructures.

The best you can do to find out is test them.If you want the best out of your phone then flash a 4.4.2 or newer if possible rom and kernel and more (I use dorimanx 10 bet test)