Here is a quick proposal

Mech classes

Standard Mech: Versitile and fast
Biped: Menuverable and can readily accept new equipments for cheaper, specialty mechs*
Quad: Faster but smaller equipment. Average weight carrying

Land Class: Powerful but slightly slower fighters
Treds: Hightened Weight Carry capacity but very slow
Wheels: Higer speed but lower versatility and weight capacity

Hover/Flying: Fast and menuvarable
Flying: Better handling Weak with very low Capacity
Hover: Higher speed but worse accuracy with slightly higher capacity

We need a third perhaps.

* = Best candidate for odd jobs like spying and assassinations and what not.

Stat system for average equipment item:

Weight: Weight
Efficency : How much energy is used
Heat output: Should your mech overheat...pain
Base Armor: Base Armor

So what do you think of W.E.H.B?
Essential items like power generators would have better stat systems of course but...

Anyway, like my ideas?