Guard. Cadian and Elysian.

Cadian because they're the standard guard force and the models were new and plastic back then.

Elysian because there wasn't anything much more fun than an army of paratroopers dropping onto the battlefield, closer than you wanted them to be and supported by Valkyries and all manner of aircraft. Thunderbolts and Lightning fighters screaming overhead to engage enemy armor, Vulture gunships hovering and letting masses of bullets form their Gatling cannons at all the fodder charging towards your troops. Cyclops demolition vehicles racing into position to detonate and decimate units in the open or in entrenched position.

Plus, air cavalry was my dream army and all the aircraft are gorgeous.