I think both films do a very good job of illustrate how far we could go to for saving the life of our love ones. For me Cloverfield had more of romantic theme whereas The Host is about family.
The message is pretty clear...No monster is going to stop us from saving our love ones. For this alone both films take the cake.
I will say this...There were some scenes in The host that really push it into the horror genre more than Cloverfield. In Cloverfield there are more jump scenes than in The host. I still like them both but for me The host gets it on the edge.