Honest
I think we should be honest. Now I'll illustrate the reasons in the following way.
Firstly, honesty is believed to be a virtue. Dishonest people are short-sighted. Those who sell fake products may make money at first, but consumers won't buy their products any more.
Secondly, honesty brings benifits in the long run. Those who always tell truth or keep to their promise not only let others trust them but gain respect from other people as well.
Besides, it is easier for a person with a good record to get a good job. Generally speaking, every employer wants his employees to be honest.
In a word, honesty wins trust, respect and honor. So it is important that we should be honest.