Remember that, at any time, someone can invent a web site title that will top your own, but you should be able to see the level of title optimization that will be required for you to gain that top spot, at least for the moment. The hyphenated version of a domain name is the more search engine friendly of the two. Some engines can only read hyphenated urls, and recognize the key phrases within them, but will only see the un-hyphenated version as a jumble of letters. Ideally your domain name will consist of, or fully contain, your primary key phrase. There are two reasons for registering the unhyphenated version in addition.
Someone guessing the URL is more likely to type it in without using the hyphens.
The second reason is to protect your domain name. It is very easy for other people to register domain names that are very similar to your own, and set up similar or competing web sites. So don't be afraid to register any similar phrases necessary to protect your own. Although this is not the ideal way for domain names to be used, there are enough unscrupulous types out there to make this a worthwhile investment. If there simply aren't any suitable domains left, then you will have to compromise.