In my experience, if your keyword is the same as your site then you probably have a better chance of ranking better in the organics. The thing to keep in mind, however, is the keyword you are choosing #1 popular and if so #2 is it still available as a domain. Bottom line, you should have a catchy domain name over all, that way it sticks with people. I think I once heard 2 -3 word domain names are sometimes easier for people to remember. NO matter what name you choose, it is going to come down to your presence on the web meaning your backlinks, etc..