Whether you have dot com dor net or dot org, it does not affect the SEO of your site. Actually domain extension is not in any way related to SEO. What matters at the end of the day is your contents that are properly optimized with on page and off page SEO. However, domain extension does affect traffic. People trust some domains more than other. For example, if they see the same contents on dot org and dot com, they will click dot org because it is from non profit organization.