Libra Dohko vs Saitama: who would win?

Saitama favored — Slight edge (~55%)

Libra Dohko · Saint Seiya · Sanctuary Arc

Tier

4-A, up to 2-A

Attack Potency

Multi-Solar System Level, up to Multiverse Level+

Speed

Speed Of Light

Durability

Multi-Solar System Level, up to Multiverse Level+

Saitama · One-Punch Man · Post-Balding

Tier

4-A, up to 3-C

Attack Potency

Multi-Solar System Level, up to Galaxy Level

Speed

Massively Ftl, up to Massively Ftl+

Durability

Multi-Solar System Level, up to Galaxy Level

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