As I explain in my book, “The Physics of Dark Shadows,” my choice would be Quentin’s staircase, which I explain is the most realistic method scientifically to travel through time (at least to the past), in that wormholes through spacetime can exist mere inches away and do not violate the laws of physics.
With the staircase (wormhole), a person can travel both through time and space at great distances by traveling through a shortcut method. This would be like walking across a temporary bridge from the top of one skyscraper to another, instead of taking the long way by traveling by elevator to the ground floor, crossing the street, and then going up the other skyscraper’s elevator. By Einstein’s theory, space and time are linked, so when you traverse space, you also traverse time.