"Which RPG has the best high tech rules? Why?"
Despite the above image reading for Shadowrun, I'm willing to pimp Interface Zero for the Savage Worlds system as well. Both have great hacking systems that incorporate aspect of the Matrix, Augmented Reality, and a dystopian worldview regarding the eventual destination of social media (Shadowrun predicting this before the advent of social media, even)
In each game, hackers/deckers 'jack in' to their respective Matrices and mess around with various systems (that, due to their worlds' interest in keeping things as automated and interconnected as possible) which perform a variety of operations, from operating streetlights to deep fryers in fast-food joints.
This concept is interesting in itself, but the crunchy depth each system goes into, whether describing the visual representation of firewalls to Intrusion Countermeasures installed in a database, or explaining how pieces of tech/custom programs interact with each other in the Matrix, is like (at least to me) taking a Comp-Sci class with no prerequisites. I'm honestly baffled by a lot of the stuff put into these, and that isn't the case with a lot of the other sci-fi games I've come across, where a spaceship is a vessel that flies in space, or a laser pistol is a handgun that shoots lasers.
It's oh so complex, but I'm hoping to crack it soon. Later, chummers.