Obviously I'd get there late and skip the Kanye part, but Iron Maiden and Taylor Swift in the same concert would be awesome. Imagine if they stayed out there and played together on all of each other's songs? Wouldn't it be awesome to hear Swift singing along on Hallowed Be Thy Name, or hear Iron Maiden backing up Cruel Summer?
The first option--but I would get there late to miss Kanye but in time to see Iron Maiden and Taylor.
Do you understand how billings work? The headliner is listed first, but they also play last, so they play in essentially reverse order as listed.