Objectively speaking, the products of the two brands are very close, and the product series Mitsubishi is slightly more. Both companies are large enterprises with chemical industry as their main business, and the water purifier is a business department under them.
The following is my personal opinion, for reference only:
Mitsubishi activated carbon should charge more for the same type of products, which should be better (if the price is the same)
Every imported Japanese product you buy will add a little tax to the Japanese government, which may be converted into the military expenditure of the Self-Defense Forces in the future.