Echo1 MP5 will be better than the galaxy MP5. The E1 will have metal bushings while the Galaxy will have plastic bushings. I'm sure the E1 will also have Madbull blue bucking installed. Overall a superior choice.
as a personal preference, i would go with echo 1 just because their guns have served me well in the past. my friend had the galaxy version however and it served it just fine. it mainly a price difference