It all depends on your point of view, from Tech, it is def Space Jockeys, then from brute force it is Engineers again, from what I have seen. Then there is the topic of Xenos being the SJ's weapons, while that is a valid point that Predators hunt them you have to think, they always hunt them before they can establish a great hive, which can take years, then the Predators come in with three of them against like 12 of the Xenos.
Anyways, before I get off topic, you have to remember that we have only seen one facility, one SP, only seen it when it had left Cryo(?) sleep, it could still have been weak, we don't know. Then there is fact that we don't actually know if Xeno's are a weapon, they could just be used as something of a pesticide originally, or a terraforming project gone wrong. We don't know, we may never know.
Back to he topic, again, so what do we know:
Extremely Advanced tech, unkown what the limits are.
Created Xenos, who knows why.
Extremely strong, who knows how strong.
My conclusion: Space Jockeys win.