Well, both are good translations (I've read volumes 1-14 and 30-36 by VIZ Media and volumes 15-29 by Chuang Yi). This decision depends on two things, where you are living and what you are looking for:
VIZ Media's books are available in many bookstores in North America and some parts of Europe and South Africa. The Chuang Yi versions are available in Singapore and parts of Southern and South-Eastern Asia, and Australia and New Zealand. If you live outside of these parts, check e-Bay or Amazon. Some bigger cities throughout the world have stores that sell imported comics (like my local store in Helsinki, Finland).
The other thing is what you're looking for. The VIZ Media bases its translation more on the games whereas Chuang Yi has its own way of translating (for example in the VIZ version Youngster Joey goes by his name in the games while the Chuang Yi uses the name Grant, also the Aqua and Magma Admins have different names from the games in the Chuang Yi version) .