Aloha! Not to sound rude but their has been multiple discussions on this topic.
A few listed from some other discussion’s was the fact that English cards have the nostalgia factor and most people can read them. Those were the main things that popped out of my head but I am sure more will be added.
www.elitefourum.com/t/japanese-value-discussion/17885/1
I do collect Japanese cards but all the exclusive promos. They love Pikachu in which I love and are only exclusive in Japanese. They also do look better (especially the borders) and are easier to grade (mainly the new back Japanese cards). I will upload a few soon.