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.
Sprinters and fast road riders who picked aero over weight. If you wanted the climbing bike in this era, compare stack/reach against the Émonda instead.
Gen 7 Madone: a pure aero race bike built on Kammtail Virtual Foil tubes with the IsoFlow cutout for rear compliance. It is the fast, heavier half of Trek's race line — Émonda is still the light bike in these years.