Neither. Unused cards don’t build credit
The only thing that builds good credit is making payments over time and avoiding late payments or other negative information. So if you’re not using the cards, they do nothing to build your credit score.
I find that it’s better to have fewer credit cards. Just too much potential for ID theft and fraud. If you don’t intend to use these cards, close them via letter and request a written confirmations that the account are closed and zero balance. Keep these confirmations forever.
Closed accounts in good standing will remain on your credit report for at least 10 years. They don’t count as much as open active accounts, but since you are not using them you probably won’t even notice the difference. See close-credit-card.html and closing-credit-card-sample-letter.html for more information.