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1. Semrush for comprehensiveness, cost, rate of development, open roadmap and responsiveness of product team ( I think I know all by name now). I also think at pace they are going they will incorporate more  off functions from smaller too.

2. varvy and dareboost - comprehensive tools  finding page speed issues

3. ranks.nl - valuable tool to analyze keywords, prominence and semantic usage

4. copyscape and site liner for dupe content issues

5. urlprofiler and screaming frog

6. search console for queries, keywords, serp ctr and internal linking

7. ahrefs and majestic for back links - unfortunately I can't recommend OSE anymore

8. Google sheets, Supermetrics and xpath

9. Annie Cushing checklists for audits

10. Moz forums and wbf

I have back correlated data to performance looking in particular at content length, keyword and phase density and prominence both overall and within different page elements against SERP rank and page performance (engagement or conversion based on whatever the particular critical measure might be). There does appear to be a minimal length of non-boiler plate text necessary to achieve both, although optimal length of content for inspection and semantic determination does not appear to be the same as page outcome, which should not be surprising.

What I have also found is that just while its possible to be too short with content, it is equally possible to be too verbose, particularly if the content begins to extend into a wide variety of topics and subtopics. My guess is that search engines have a harder time deciding what the message of a page is when it turns into an encyclopedia.