Sons of Behemat represent the ideal low model count army, with even the largest only hitting under 10 models at 2000 points you really have a decent chance to personalise every model in the force. With their massive frames there is an opportunity to tell of their legend through stolen trophies and artefacts, body paint and wounds and even mutations to reflect different breeds of Gargants roaming the realms.
With so much room to explore in the mortal realms it is entirely possible to create your own narrative species of Gargant, from the Frost Gargant shown below through various elemental, mutated or even factional allegiant Gargants to join your other forces. Whatever your end result the massive frame of the Mega Gargant kit makes it a true centrepiece in your army.