I guess that for Army 1, you have actually meant to select Serpent Riders, and not Serpent Guards?
If so, is not the total 303 points, which would normally not be allowed for a tournament..?
I would go for Army 2, because it does not contain Fell Wargs
But I do like the Betrayer and his Special Rules, which can boost your wounding, which you need.. So perhaps if you got rid of the Fell Wargs, as you did want an all mounted Harad army..
For Army 2 you could drop the Bow on the Haradrim King, and field another Haradrim Raider, so that you increase the points to a total of exactly 300.
Not sure how competitive that list would be, but at least it would be a balanced one.