NZXT Guardian or CM Storm Enforcer?

CM Storm Enforcer would be my choice, its bit bigger, 1 inch wider allows taller CPU cooler.

+ Quiet.
+ Removable tray for better airflow or for big card.
+ Fits large cards and coolers.
+ Fully painted interior
+ Removable 3.5" drives bays and relocatable 2.5" bays
+ One of the only mid-tower cases that can handle the longest graphics cards
+ USB 3.0 x 2, USB 2.0 x 2
+ Excellent cable management features
+ Excellent value for price

Cooler_Master_Storm_Enforcer_SGC-1000-KWN1_open_case_test_setup.jpg