If you are using WordPress for SEO, you can consider 3 plugin that I always use. Below is mine checklist of these 3 plugin, hope can help you make correct decision.
| SEO Plugin Features | All-in-One SEO | Yoast WordPress SEO | SEO Ultimate |
| Google Analytics | Yes | Yes | No |
| Webmaster Tools | Yes | Yes | No |
| Sitemap XML submission | Yes | Yes | No |
| Keyword recommendations for pages | Yes | Yes | No |
| Good interface usability | Yes | Yes | No |
| Beginner-friendly, ease-of-use | Yes | No | No |
| Page titles and slugs | Yes | Yes | Yes |
| Meta descriptions | Yes | Yes | Yes |
| Canonicalization | Yes | Yes | Yes |
| Blog category/archives/tags indexing, singular URLs and nonduplication | Yes | Yes | Yes |
| On-page SEO recommendation | No | Yes | No |
| Image alt tags | Yes | Yes | No |
| Page Nofollow/noindex | Yes | Yes | Yes |
| AutoTags | No | No | Yes |