Got a HAF-X myself, love the thing.
In terms of air cooling, there shouldnt be any real difference between them. More airflow beyond a point just doesn't do anything. Water-cooling support is the real difference between the cases. The Stryker cant hold a triple rad at the top, the HAF-X can.
So if water isnt a concern, go with whichever you think looks better. There will be no real difference between the two once you close the side panel. If custom water is a concern, then go for the HAF-X.