Da Vinci
The Da Vinci, alone and unsupported, is one of the easier NPC models to kill, as its only direct fire weapon is its front mount MG.
Therefore, it's cruelly ironic that the Da Vinci is one of the most dangerous models to encounter when it's backing up a squad of enemies with its Paint Gun.
A Da Vinci unchecked can spell defeat for a squad of players. The Paint Gun effectively disable the target's weapons for several turns, and this is why the Da Vinci so very dangerous.
On the other hand, it's slow and handles poorly over difficult terrain, and it tends to lag behind its consorts quite a bit, especially once the shots start flying. It's a great target for a muscle car or two to get around the heavies and rip the Da Vinci open. Even inducing a Da Vinci to turn away from your allies can make a huge difference, and once you're inside 40 meters, the Paint Gun accuracy goes down sharply. Don't get too close to its flanks or the Paint Sprays will gum up your weapons, but otherwise, it's a fat and easy target.