Yuji Kiba vs Kishou Arima: who would win?

Yuji Kiba favored — Slight edge (~55%)

Yuji Kiba · Kamen Rider · Horse Orphnoch

Tier
7-C
Attack Potency
Town Level+
Speed
Relativistic+
Durability
Town Level+

Kishou Arima · Tokyo Ghoul · Base

Tier
7-C, up to HIGH 7-C
Attack Potency
Large Town Level, up to Town Level+
Speed
Massively Hypersonic+, up to Sub-Relativistic
Durability
Large Town Level, up to Town Level+

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