I'd quite like to see some higher profile comic artists. If we could get Jim Lee and some of the DC people to do a panel, that would be quite cool, especially given the success of Rebirth this year.
seeing as though it's the 25th anniversary of Batman the animated series. Paul Dini, Mark Hamill, Kevin Conroy would be good too
Also some ex and current WWE guys like Shawn Michaels, Hulk Hogan, Steve Austin (all unlikely but cool.)
Movie wise I'd quite like to see:
Henry Cavill
Ben Affleck
Daisy Ridley
John Boyega
Benerdict Cumberbatch
TV
Marvel Netflix Cast members
Peter Capaldi
Stephen Amell