Research depth
Discovery
How well the tool supports keyword, competitor, SERP, backlink, or market research before execution.
Nightwatch
Strong first-party search intelligence: daily verified rankings, raw SERP snapshots, keyword research and site audits.
99.9% accuracy, archived raw HTML SERP snapshots, 4.5B+ keyword database and audit tooling are described at https://nightwatch.io/ and https://nightwatch.io/keyword-research/
Siteimprove SEO
Strong enterprise SEO research coverage across competitors, SERPs, keywords, content gaps, and paid/organic data.
The SEO analytics page promises complete competitor strategies, deep SERP analysis, keyword monitoring, and paid/organic data: https://www.siteimprove.com/platform/seo/seo-analytics-tool/