Some people think it is incredibly important to have keywords in a domain. People purchase domains like look-4-buy-cheap-discount-viagra-online-pharmacy.com. This is a horrible domain name!
An exact matching domain name in a competitive market can be seen by Google as a signal of quality. Since acquiring one would either indicate that you were early to the market or paid a premium for the URL. Some strong .com names sell for millions of dollars. On the other hand associated .net and .org domains can range from a few hundred dollars to a hundred thousand dollars.
If your site exhibits a number of strong brand related characteristics, such as high search volume for brand related keywords, high clickthrough rate for core brand related searches, many repeat visitors, or relevant matching URL and/or anchor text, there is a good chance that Google will place a set of Sitelinks in the search results for brand related search queries.
Keywords in the domain name may help some (as people tend to link to websites using their official names as the link text), but if I were going to create a long-term business, I would put brand above keyword-rich, unless you can find a name that exactly matched your core keywords or something that allows you to leverage both assets.
If you are creative, you usually can get keywords in the domain while keeping it short, memorable, fairly brandable, and free of hyphens.
Dashed Domain Names
Direct marketing mail campaigns usually peak in effectiveness around the third exposure to a marketing message. Many shoppers look around. If you want them to come back, you want to have a domain name that will stick in their heads. It can have keywords in it, but the thing you want more than anything else is a name that sticks.
If the option between having the dash in the domain and not having a dash exists, you are probably better off going without the dash as it looks more professional and would most likely be more memorable.
It is branding suicide to only have users find your site via search engines. If you are hoping to make sales on the first view in search engines, you need strong copywriting and usability.
If you are just using quick-buck-lead-generation websites then you may want to use a keyword-rich hyphenated domain for the small benefit it may offer, but in most cases, I do not recommend a hyphenated domain name for long-term websites.
Long versus Short URLs
People will forget the words in a domain name that is exceptionally long. Another problem with exceptionally long URLs is that they get cut off in e-mails and some other data transmission types. If you make the idea hard to spread, then you limit your site’s potential income.
The Best of Both Worlds!
What if you could get some of the benefits of a long keyword rich domain while still using a shorter and easy to brand domain name? You can! If you use a short, branded domain, you can still include your keywords in your page title and logo to help control how some people link at your site. For example, a company like PayPal can register the domain Paypal.com, but put the words payment solutions or online payments in their logo near the word PayPal. Some people will reference them with those words as part of the company name. Search engines associate words that occur near one another. For example, Google showed the following as suggested advertisements.
On the far right notice how Google realized that my name and the name of my strongest brand are related.
If you can work your name or your company name into the default topical vocabulary of a search, you will have a strong advantage over your competitors.
Source: Search Engine Optimization Book, Aaron Matthew Wall