What would a programmer rather work on. Some boring app for someone else, or an app to solve a problem he has of his own. What is more enjoyable, working on th

What would a programmer rather work on. Some boring app for someone else, or an app to solve a problem he has of his own. What is more enjoyable, working on the language and database dictated by work, or whatever tech he wants to use. As long as a person gets out of bed and does a days work doing something productive in some way, it doesn't matter that it's not traditional work.