I also quite like the Justice version:

Nice

I prefer his design from the DCAU superman and justice league cartoon

I love the metallic skeleton design. Such a terrifying change for Brainiac

I like his first appearance and metal skeleton design. But my favourite has to be his design from superman '78.

I really like the costume design for Injustice Brainiac, but I don't like how muscular he is. It feels like it takes the attention away from his overwhelming intellect.