If you put security first and simple, you should try Huobi. In Huobi you need email verification, 2FA and HP number to be able to withdraw the transaction

If you give priority to security, you should try Bittrex. In Bittrex you have to verify your private data, and every time you login with a different IP you have to confirm via email,

If you prefer simple, then I recommend Etherdelta for Ethereum-based coins and also HitBTC for other coins. In both exchangers you do not need any complicated verification, so the withdraw process can be done easily