Einar

Supreme.

At least in my head.:-)

Wikipedia has the actual answer:

‘S’ tier may stand for “special”, “super”, or the Japanese word for “exemplary” (秀, shū), and originates from the widespread use in Japanese culture of an ‘S’ grade for advertising and academic grading.

• https://en.wikipedia.org/wiki/Tier_list

Skynet seems like a fair prediction.