Here is a shot of various figs with a ruler in the background. The shot was a little above the ground and it was from the bottom of the bases(20mm fender washers) so the ruler will not be 100% accurate but it should give a good idea of relative scale.
From left to right (FOW German riflemen, FOW American Para, GZG New Israeli, Alternative Armies Automoton, Command Decision British Para, GZG japanese, MW clix battle armor, MW clix Battle armor, MW clix Ravager battle armor(the big one), MW clix battle armor, MW clix grey death battle armor, GZG Kravak trooper, GZG UNSC trooper, GZG FCT trooper, GZG Kravak Power Armor)
From left to Right: GZG Phalon, Spug, Zombiesmith Aphid(2)
Left to Right: GZG Phalon, GZG FSE trooper, Spug, Aphid, FOW US paratrooper
Left to Right: FOW US paratrooper, GZG FSE, spug, Heavy Gear, MW clix Ravager
From left to Right: US Spec Ops(Rebel Minis), Heavy Gear, New Israeli(GZG), UNSC (GZG), FCT (GZG), Contractor Merc (Rebel Minis), Ambush Alley Freebie(Rebel Minis?),US Spec Ops(Rebel Minis), US Spec Ops(Rebel Minis)