A two-tail P value is more consistent with the P values reported by these tests. Choosing a one-tail P value can pose a dilemma. To be rigorous, you should conclude that the difference is due to chance, and that the difference is not statistically significant. But most people would be tempted to switch to a two-tail P value or to reverse the direction of the experimental hypothesis. You avoid this situation by always using two-tail P values.
Statistical hypothesis testing The P value is a fraction.
In many situations, the best thing to do is report that number to summarize the results of a comparison. In other situations, you'll want to make a decision based on a single comparison. In these situations, follow the steps of statistical hypothesis testing. P value before you do the experiment. Ideally, you should set this value based on the relative consequences of missing a true difference or falsely finding a difference.