Riesbyfe Stridberg vs Seiichi Samura: who would win?

Riesbyfe Stridberg favored — Slight edge (~55%)

Riesbyfe Stridberg · Nasuverse · Base

Tier
9-A
Attack Potency
Small Building Level
Speed
Ftl
Durability
Small Building Level

Seiichi Samura · Kagurabachi · Base

Tier
9-A, up to 7-B
Attack Potency
Small Building Level, up to City Level
Speed
Massively Hypersonic+, up to Sub-Relativistic
Durability
Small Building Level, up to City Level

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