Debit is only for those who cannot control or get credit.
That wasn't his question. His question was whether he should choose debit or credit when using his debit card for a transaction.
To the OP. I choose credit because I like to skip the PIN step. When debit cards were newer and this option came out I always chose credit because I was told that the transaction fees went on the seller if you chose credit. I cannot confirm this information as true but I got in the habit of choosing the credit option and still do to this day.