SEO Powersuite is the most effective tool for seo.It includes -
1. Rank Tracker that allow you to analyze rank of your site for multiple keywords.
2. SEO SpyGlass that helps you to audit backlinks for your sites.
3. BuzzBundle helps to find the current trends and mentions with competitor analysis.
4. Website Auditor lets you to audit your website from seo perspective.
SEO Powersuite is the all in one seo combo tool that you should use.