If Anything Were Possible, What Would You Wish?
This one is mega simple.
I would be able to apparate.
As someone who has spent YEARS on public transport, I would wish to be able to teleport anywhere I wanted with anyone I wanted to in a second. No international rules.
It would be awesome, because I could go to Angor Wak in Cambodia for the day, then come home to my bed to sleep. Imagine! Endless holidays, with no hotel fees, because you can just apparate back home at bedtime. I could pop to Australia and go to a bar with my friend and be back in the afternoon to teach classes. I could apparate to awesome dance classes in other countries. After a stressful day at work I could apparate to Hawaii to relax and watch the sunset.
It would be AMAZING.
Even better than being able to fly.