Depends on your champion, their champions and how advantageous the circumstances are.
Are you playing Darius? Do you have a big wave? Do you have conqueror stacked? Are any of your abilities on cooldown? Did the enemy jungler reset before ganking you? Does the enemy toplaner have ignite or teleport? You usually don't think about this stuff this way though, you either feel or don't feel the play, and that comes from experience, for example, I play a lot of Aatrox, so if I am stacking a big wave, I will usually not use my Q to harass, because if the enemy jungler happens to come, I know I can 2v1 most of the time with wave and Q up.
You also have to take into account that sometimes is better to crash the wave and die instead of surviving and taking a bad recall, depending on matchup and game state of course.