For me there is only one functional and fully operational exchange and that is the bitshares DEX and the best wallet provider so far is Open.ledger. Whether you choose as your wallet provider Open.ledger or freedomledger or soon moonstone or another Chinese one I think called btsabc all are based on bitshares technology. With bitshares DEX you can convert your bitcoins to bitbtc and know that they will be worth at least the equivalent btc.

bitbtc is the decentralized btc derivative. That is the decentralized asset. Open.btc is the IOU of the btc from Open ledger. If you have bit.xxxx assets whether they are bit.btc, bit.gold, bit.usd, bit.cny etc then your funds are secured (unless you are targeted, hacked, lose your password etc..) but definitely more secure than holding your cryptos in external exchanges..