Which Keyword is better?

Exactly! This is your best answer

 

You should be optimizing with both. If you are using adsense, you should do the same.

 

Use the keyword analysis tool, or better yet use keyword spy to find out which one your competitors are optimizing for most. Then choose to either dominate the one not being used most, or try to beat them at their own words.

 

I think credit card is better but you also can check it in Google Adwords

 

BH: I think we need the context of how the name will be used - in order to determine which one fits. I can make a case for either one depending upon what your site
will explicitly be selling or implicitly recruiting customers for.