personally https://www.Preapaid2Coin.com (Prepaid2Coin) is the only U.S. owned company that buys all prepaid cards (including Vanilla Direct) in exchange for bitcoin directly to your wallet.   Most other sites are either card swapping sites or based in Nigeria. 

Prepaid2coin.com is the only US based website where you can directly sell your gift cards (including Vanilla Direct cards) for bitcoin.   They are US based, PCI compliant and are NOT a SWAPPING site.   it's easy and way safer than swapping sites.