Which case runs cooler?

too broad of a question.

Is that because they are too similar?

No, you need to pick a model from antec and a model from cooler master, then we can make a comparison, but a comparison across the whole brand is impossible.

They brand names are just my place holders for the hyperlinks to the specific cases.

OK, got it.

I'd say they are roughly equivalent in their air handling abilities. They both have more than one intake and more than one outflow fans, so that is good. I would go by which case meets your needs best in terms of front panel ports and general styling.

They both have good airflow. Go for Antec 900.. it has front USB 3.0

Agreed and I'm just happy when someone dosn't get the haf  

Haha why?  

there a bellybutton case . ( everyone has one ) . Also I find them to be almost criminally ugly .

^They really are pretty ugly.. Although I'm pretty sure the antec is more popular. Look how many reviews it has on Newegg!!

I think ( and I could be wrong ) that antec has been around longer also there sold at retail locations like bestbuy ..My personal preferences aside the haf is popular for a reason that I cant dispute . I just prefer something that dosnt look like it belongs on the playground