Crew neck t-shirts tend to get wrinkly and don't give you a clean, sleek look. It's better to have a v neck shirt showing your chest.
I will say though that sometimes I will wear a crew neck shirt if the color or design looks good against the shirt. Also depends on how much of the shirt will be seen when the button down is unbuttoned at the top. The crew shouldn't be too loose either because when you bend forward (as thearticle points out) it will hang open. And then people can see your chest stomach etc. Not too dignified lol