Roy Alphard vs Akemura Soga: who would win?

Akemura Soga favored — Slight edge (~55%)

Roy Alphard · Re:Zero kara Hajimeru Isekai Seikatsu · Base

Tier
7-B, up to 7-A
Attack Potency
City Level, up to Mountain Level
Speed
Superhuman, up to Relativistic+
Durability
City Level+, up to Mountain Level

Akemura Soga · Kagurabachi · Base

Tier
7-B
Attack Potency
City Level
Speed
Sub-Relativistic
Durability
City Level

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