Here's my Post-Credit entry. It follows the aftermath of Civil War. It could very well be Ant-Man's Post-Credit as well but introducing this character would make more sense following Civil War.
We see overhead shots of various cities, where battles occurred. There is a purplish hue in the shot to give the illusion someone is seeing this telepathically.
Narrator: This war was futile, meaningless, how can we anticipate a larger threat when we couldn't even learn to work together here?"
The camera zooms in on New York City. It zooms further into Greenwich Village, finally on a victorian style looking townhouse. A new shot shows the address "177A Bleecker St."
Interior of 177A Bleecker St.
Camera moves down a hallway towards a larger room, there are book shelves everywhere, ancient trinkets, Marvel Easter Eggs, etc.
Narrator: The world isn't ready for the rising storm coming from beyond...
Camera enters the large room to see a cloaked man levitating, deep in meditation, there is a ring of yellow light on the floor circling him which ancient symbols. Camera circles around to the front of the man and begins moving upward, we see the "Eye of Agamotto" glowing.
Narrator: This is a war in which science alone will not find itself victorious. Are you ready, Doctor?
Camera reaches Dr. Stephen Strange's face, his eyes open.
Narrator: It is Time.
Cut to Black.
So there you have it, that's my take on what an epic post credit scene would consist of. Helps build into Doctor Strange, as well as hints once again for the oncoming Infinity War, whom Strange in the comics has a big involvement in. The Narrator could be anyone, but most likely Dr Strange's mentor.
This was my first post to movie pilot after years of being an avid reader. Hope you all enjoyed this. Cheers.