If I had to choose a door to step through I would choose the door to Narnia. Imagine stepping out into an entire different world, new creatures and a completely different universe. You could stay in Narnia for an eternity and the moment you step out it reacts as if you haven't even been gone for 10 minutes. Time literally stops, you could live as an older self in an alternate universe. This appeals to me because it would be awesome to escape reality and be a queen of Narnia and it wouldn't even take a moment of your time. You could meet amazing creatures and make new friends, it would be awesome.