vs Strogg: http://quake.wikia.com/wiki/Strogg
Which faction would win in a full scale war?
Situation #1: The Scrin invade Stroggos. http://quake.wikia.com/wiki/Stroggos
Situation #2: The Scrin have occupied Earth. There are no humans. The Strogg invade "Scrin Earth."
Scrin vs Strogg. Who will be the victor?
Edit: I understand that there is a lot of info to go through on both these alien races. So take your time and learn about each of these races and their capabilities.