I assume that .com domain extension is the most preferable one.. You know, there are many factors that influence on your SEO ranking.
.Com is preferred but there are lot of other factors affects keyword ranking. You can rank keywords by having .net extension also.
You whant to start a SEO Service Site and you ask such dumb question ? In SEO TLD doesn't mather For Branding .com is the favorite ..
nothing is better than .com domain. It should always be the first priority. Even if you buy the domain, .com domains are costly than others
Good one! It depends, if you want to offer your services globally I would recommend .com, though I have also used other neutral domains such as .net and .biz with success. If you offer services locally (e.g., in a specific country) then try a ccTLD.