By all accounts the Virago is a great bike for the money undercutting
Halfords Boardman which was previously their cheapest carbon framed bike.
If you don’t mind riding a Halfords name then it’s got a lot going for it. Don’t get too hung up on carbon though.
The Virago doesn’t look to have mudguard mounts, the Synapse does. Rim brakes on the Virago and cable discs on the Cannondale.
The Halfords bike has quite a racy geometry with 25c tyres so won’t be too comfy on poor surfaces. The Cannondale is more relaxed with 28c tyres.
Warranties look comparable.
The choice is yours. Both are great bikes.