I'm going to approach this question literally - which events are hardest to plan... For me it's the events where your clients/stakeholders are very emotionally attached. The stakes are very high for a wedding - you have a client who may consider this the most important day of her life. Compare this with a corporate event - those have a different kind of high stakes, but a lot less of the heightened emotions surrounding it. So, for me, corporate is the way to go. However, you also have to look at what gives you personal satisfaction. Perhaps working with a bride and her family give YOU the professional satisfaction you desire and a more cut and dried corporate event is less fulfilling for you. When you are just starting out, working at a company or venue that handles both corporate and private events may give you a good feeling of the kind of events that you find personally satisfying. Because the hardest events to plan are often the ones that you, as a planner, don't feel connected to.