Research depth
Discovery
How well the tool supports keyword, competitor, SERP, backlink, or market research before execution.
KWHero
Strong research workflow with keyword ideas, SERP data, clustering, and topical maps.
The homepage says users can discover opportunities with keyword ideas, SERP data, and AI-powered Topic Clusters, and can analyze search volume, difficulty, and SERPs: https://kwhero.com/
seoClarity
Very deep first-party SEO research coverage.
The keyword research page documents AI Topic Research, Research Grid, content gaps, content ideas, keyword difficulty, answer-box opportunities, video keywords, 30+ billion clickstream data, 500 million Research Grid keywords, and 1 billion Google Suggest keywords: https://www.seoclarity.net/keyword-research/