Revisiting Google and Hyphenated Domain names

use '-' or not for domain name registration

[rezash]

Hi competitors,
I would like to register a domain using 3 main keywords and please tell me which one is better for google SE:

1- www.keyword1keyword2keyword3.com
2- www.keyword1-keyword2-keyword3.com

or they are same.

thanks for any advice
-Reza