What is best thing to do with business credit cards that you aren't using?

(This is for a business (LLC; has an EIN) that is in operation and needs credit card access, so not a business for the purpose of getting business cards/SUBs)

I've got a two business credit cards. One of them is the "daily driver". One of them is idle/unused as I initially got it for a 0% APR offer for larger purchases to spread the payment out over time. Now, getting a third card to "roll over" 0% APR availability.

All 3 cards are from different banks.

Is it better to keep the idle card active, or just close it out?

On one hand, I think that having the card active would facilitate further applications since you're already a customer/account holder.

On the other, having too many cards may be a problem for opening new accounts?

What's the best practice here?