Research depth
Discovery
How well the tool supports keyword, competitor, SERP, backlink, or market research before execution.
MarketMuse
Deep topic, SERP, competitor, site-inventory, cluster, and content-quality research is central to the product.
Content planning says it performs keyword, competitor, and SERP research and supplies cluster details and competitive overview; https://www.marketmuse.com/content-planning/
SpyFu
Broad historical competitor SEO/PPC dataset and many research views.
The homepage says users can see competitors' SEO/PPC keywords and every ad they have tested; https://www.spyfu.com/