Research depth
Discovery
How well the tool supports keyword, competitor, SERP, backlink, or market research before execution.
Screpy
Covers keyword research, SERP analysis, organic keywords, competitor ads, backlinks, referring domains, and Search Console, but depth and quotas vary by plan.
Feature directory lists Keyword Research, SERP Analysis, Organic Keywords, Competitor Ads, Backlink Checker, Referring Domains, and Search Console: https://screpy.com/features/
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/