There has been discussion between the two since the release of the firewalker pack, some say that the Mako is better, while others say the Hammerhead is better.
The armour is tough enough to withstand high drops, extreme heat and cold and rough terrain, also environmentally sealed.
The suspension and propulsion system allow the vehicle to adapt to various terrain.
The Mako has strong kinetic barriers that can survive multiple hits before they collapse.
The Hammerhead is armed with a single gun which can only swivel vertically, but it compensates for this by boasting a fairly high rate of fire and a guided missile system.
The Hammerhead's hoverjets allows the Hammerhead to hover over the battlefield at up to 120 kilometers an hour.
Hammerhead has sophisticated repair system which automatically restores the vehicle's integrity.
I personal prefer the M35 Mako, it was a pain to drive but it could take hits and deal them back out with it's cannon, the coaxial-mounted machine gun knocked off infantry off their feet leaving them open to a shot from the cannon (Overkill much?).
Although the M-44 Hammerhead does have better handling than the Mako, but under fire it feels like it was made out tissue paper.
And because of that I like the Mako.