head to head
Neither is simply harder - they are hard in different places. Portal demands more execution; Songs of Conquest demands more variance.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.

Optimization · Pure Optimization
Optimizing Wielder builds and resource networks to project force in PvP or solo campaigns.
Portal leans Optimization (Pure Optimization); Songs of Conquest leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Portal
Portal placement timing modest.
Songs of Conquest
Turn-based throughout; no timing demands
Songs of Conquest leans clearly harder on reads.
Portal
No adversary modeling player.
Songs of Conquest
Human PvP multiplayer creates opponent prediction pressure
Songs of Conquest leans clearly harder on variance.
Portal
Deterministic chambers; no randomness.
Songs of Conquest
Resource tile placement and battle spell procs add variance
Songs of Conquest leans a little harder on optimization, though the gap is small.
Portal
Pure puzzle-solving optimization.
Songs of Conquest
Wielder skill trees, unit stacking, and map control routing are the optimization core
A matching score does not mean a matching test. Two games can both sit at 10 on execution and demand completely different things of you - which is why the reasoning above matters more than the number beside it.