A simulation is useful when you can see what it chooses to change.
Film simulations are coordinated rendering choices, not magic labels. They decide how reds, greens, blues, skin, highlights, and shadows relate to one another. Two recipes can share similar contrast and still tell completely different color stories.
Use a photograph you know well and keep the divider moving. Reala Ace offers a balanced reference; Classic Negative makes color more nostalgic; Astia protects soft portraits; Eterna lowers the volume for a cinema-oriented starting point. None is correct for every frame.