Sakura Matou vs Steel Guardian: who would win?

Steel Guardian favored — Slight edge (~55%)

Sakura Matou · Nasuverse · Dark Sakura

Tier

9-A, up to HIGH 6-C

Attack Potency

Small Building Level, up to Large Island Level

Speed

Subsonic, up to Ftl

Durability

Human Level, up to Large Island Level

Steel Guardian · Silent Hill · Base

Tier

9-A

Attack Potency

Small Building Level

Speed

Athletic Human

Durability

Small Building Level

A heuristic estimate from normalized VS Battles Wiki stats: tier, attack potency, speed and durability.