Every industry/niche differs in the way domains should be named, especially if that industry is highly competitive. In such situations you don’t have much options since the short words of generic Top Level Domains like .com, .net and .org are already taken. Domainers (the profession dealing and trading domain names) say that the most valuable domains are the single word keywords, then the two words and so on. Basically if you follow that pattern, using your own product niche keywords and the available for registration domain names, you must chose the shortest most descriptive one as primary. Now note that I’m saying primary, and that’s intentional.

Every webmaster should have atleast two websites for each niche. One as primary selling/service or whatever domain, and atleast one Reviews domain which will be used later on in the marketing and SEO process. The reviews domain should be slightly longer than the primary and should contain highly searched keyword combination. Note that domains longer than 4 words are considered spammy and might not be accepted well by the search engines, so keep em short.