Its all about whatever looks better. Well there are people who actually use 100% of the extra features but for those people they would know what case they were "required" to choose.
The people who need 6 3.5 drive bays would know to choose a case that had that specific feature (400R) over say one that doesn't (haf 922 has 5)
So if you can't think of anything else that you might need it comes down to aesthetics.