Top ranking keyword
I would like to see what the highest ranking keyword actually is - not just a number in the top 100
On-Page Checker like SEO Minion tool bar have mixed with the YoastSEO real content analysis with a keyword placement checker/counter and METAS reviewer. Yes, that's all.
Please Include Total Number of Keyword Rankings with Top 5 Keywords Name Mentioning
Top rankings keywords number with mentioning of top 5 keywords names. I think this you can do in a free version.
Custom HTTP header
It's useful to set a custom header when browsing a website, e.g. a website that respects accept-language will need a blank value sent to see what Googlebot would see. I currently use https://modheader.com/ extension to achieve the same. Would be nice to have fewer extensions.
It'd be great if in the on page SEO data we could quickly see if a page has structured data or schema.
On-Page Optimization Score
Basically exactly what Moz has in the chrome tool bar where you punch in a KW and it gives you a score and on-page suggestions to fix.
Show top keyword suggestions in the SERP (along with other keyword data)
Ahrefs Toolbar could show keyword suggestions for the search query in the SERP directly.