Apart from the head, I would argue that the Engineers are even more Alien than the original Space Jockey when in their jumpsuits, which offer an extremely giger-esque aesthetic, more so than the bio suit's huge ribcage and elephantine head-piece.
Honestly I think their design serves best to whichever movie they are in.
I wasn't too upset by the design re-interpretation as the Space Jockey from Alien was essentially a man with a huge ribcage and elephantine head, nothing else alien about him apart from the odd patterns on his arms. When the Engineers were in their suits in Prometheus we essentially got the same thing, only their air of "Alien" was replaced with mystique and their scale was different.