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.
CX racers. If you want gravel capability, look at Checkpoint or Checkmate instead.
A UCI cyclocross race bike with IsoSpeed on some generations. Tight, muddy, and built to be shouldered — not a Checkpoint with CX tires.
Gravel riders who want Giant's drop-bar all-road, not a TCR with knobbies.
Giant's gravel bike: stable, mounts, and a position between Defy and a race gravel whip. The X variants add more suspension/travel attitude.
CX and gravel racers who size like a road-race bike. If you want Future Shock and mounts, Diverge is the sibling.
The light gravel/CX race bike: lower and snappier than Diverge, with less adventure hardware. It feels like a Tarmac that grew tire clearance.