Racers and fit riders who want Giant's race geometry without Propel's deep tubes.
Giant's lightweight race bike: compact sloping top tube, sharp steering, and a fit that has been a stack/reach reference for a long time. Less aero drama than Propel.
Racers who like Cannondale's handling. Synapse is the taller sibling; SuperX is the CX/gravel race cousin.
The third-generation EVO: dropped seatstays and truncated-airfoil tubes turned Cannondale's climbing bike into an aero all-rounder with room for 30 mm tires. Lively rather than deep-aero.