Why and when is xbow better than an archer (Warden)?

[Bobo]

The biggest differences for me are: Pavise able to save the team if there's no other shielder and the aiming time - you can shoot as fast as you can place the crosshair on the target. The latter extremely useful when facing the most dangerous enemy ranged untis (e.g. Ballistamen). Otherwise archers are more deadly class thank to the speed and a kiteable one.