Either....
The original style Mad Dog (God, why did MW4 have to convince Legions of people it's a long range support mech only?)
OR
The Shadowcat variant I usually ran in tourneys, which dropped the Lasers for masses of Machine Guns. Jump behind an Assault Mech, Called Shot, Gauss Rifle the rear armour, empty all the Machine Guns into the Internals for maximum number of Crit rolls, watch as their ammo explodes.

- Shockwave