They both kinda out of the meta, with Tsunade occasionally being used in arena, Karin even less so. The latter can be very useful for ninja exams, the former too to a certain extent. Is that warrant the price tag? That's subjective and up to u to decide. If you recharging and can easily afford them there's no reason to not pick them up. If you have to ration your coupons more, then there's a case to be made for the power packs - assuming you're not interested in Orochimaru either.

Yea, I already have Orochimaru to 4* so no need for him in the packs.

I kind of want Karin purely because I like the character in the show and she could help my Ranked Battle team tremendously but I dunno if I should save my last bits of Coupons/Ingots or go for it. There's also a lot of power items in Fuku's that could help me a lot.

Then it ain't worth it for you. If the choice is to pick power packs or a ninja to reinforce your ranked team the decision is obvious.