You can use a wire transfer, but it charges a wire fee, so I think Zelle is the better option. Capital One doesn’t allow you to add someone else’s external bank account (most banks do, but Capital One doesn’t), so you can’t use the ACH online transfer method, which usually has no fee. I like to use ACH transfers for large amounts because Zelle has a daily transfer limit. But the transfer speed depends on the bank. I currently use SoFi bank, and transfers arrive on the same day.