A High Voltage AC or a High Voltage DC which is more dangerous for human?
Both will potentially kill you, but in that voltage region where it will not instantaneously kill you, the so-called let-go threshold is the most relevant. We were though in school that DC will cause harder cramps but measured and observed results tells otherwise. See here
When you are have touched a conductor at that voltage, you might be stuck there waiting for someone to break the voltage or your own death, whichever comes first.

EDIT: Revised answer from PlasmaHH's link. Thanks!