Funding an account with an exchange, or directly sending payment for transactions: which would you prefer?

With fiat currency, its a no-brainer, especially if you intend to trade in and out, since bank transfers take so long, but what about from the bitcoin side? Would you prefer to directly send btc from your wallet to the market for fiat currency, or transfer it to the exchange's wallet first, and then trading with the market?

Curious to hear what everyone's preference is.