This can be tricky because all platforms have pros and cons and the company or client may have a specific favorite in mind. Event marketing is key and social media is a valuable tool so make your experience clear in which you have dealt with and where you have seen the most success. If the role involves a level of event marketing you will need to highlight that you are adaptable to other social media platforms to suit the needs of the event and audience. If your personal social media accounts are public make sure that your own channels show some of your flair and skills for social media.