Research depth
Discovery
How well the tool supports keyword, competitor, SERP, backlink, or market research before execution.
ChangeTower
Provides monitoring snapshots and change reports rather than broad SEO research datasets.
The product describes crawling URLs and capturing visual, text and source-code snapshots, but not a broad SEO research database: https://changetower.com/
Google Ads Keyword Planner
Useful search-demand and idea research inside an advertising workflow, without broader SEO research coverage.
Google documents keyword ideas, search frequency, trend, and campaign-forecast data for Google Ads. https://ads.google.com/home/tools/keyword-planner/