I was preferring elite 430 over 431 just cause 430 looks better to me.
so now i have these choices -
-nzxt beta evo
-nzxt tempest 210
-coolermaster 430 elite
-nzxt source 220
-antec 100 lite/antec 300
If i were buying a case today i'd definitely choose one with USB 3.0.
If that doesn't matter to you buy whatever you prefer.
Cases that include two fans are a better value imo if the cost is the same.
If the 431 was available when i bought my 430 i would have chosen it.
Not much change other then the front panel inclusion of USB 3.0 and relocation of power and reset buttons.
Window side panel doesn't have fan mount on 431,i think it's nicer looking.(reduces dust intake,improves airflow,probably quieter)