How about wasabi and squid? That's 9 points on two cards. Also, green tea ice cream and onigiri are worth 4 points each card when scoring optimally.
Green Tea Ice Cream is only three points per card.
I don't think the question of whether Uramaki are more powerful than Maki is a super relevant one because they'll never be on the same menu, and they provide different types of gameplay. Uramaki might be more tempting to go for, but in a game with Maki you'll have your own unique considerations.