I voted for ICON, but in all honesty, they're all must-sees for me. ICON, Downtown Clowntown, and Sideshow of Decay are so connected to one another from the lore/anniversary side of things that there will be interesting things to see in all of them. Fortnitemares from the pure people-watching side of things. How are people going to react? How is this scarezone going to evolve each night or over multiple nights? I mean, the possibilities are endless (which is fitting for Fortnite).
If they start doing Battle Royales in this scarezone, that could be a ton of fun.