Armin Arlert vs Stevonnie: who would win?

Stevonnie favored — Slight edge (~55%)

Armin Arlert · Attack on Titan · Titan Form

Tier

HIGH 7-C

Attack Potency

Large Town Level

Speed

Subsonic, up to Supersonic

Durability

City Block Level+

Stevonnie · Steven Universe · Base

Tier

HIGH 7-C

Attack Potency

Large Town Level

Speed

Superhuman, up to Relativistic+

Durability

Large Town Level, up to Island Level

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