It should be an essential tool for all website owners - everyone should care about page loading time from the CEO down to the junior web developer. Page speed is a factor that hugely affects visitor satisfaction, and Google takes it seriously by offering PageSpeed Insights. If you work in a larger organisation and focus on one particular part of website development and maintenance, such as a content writer, then this tool won't be as useful. It's intended for users with development or marketing-related responsibility
Squirrly SEO is especially suited for a WordPress website owner wanting to up their SEO game, but not knowing where to start. Squirrly does a great job of walking a beginner user through the steps to meet their site optimization goals one focus page at a time. Once, you get over the dated UI Squirrly really offers more than other WordPress SEO plugins.
I've never used any software beyond PageSpeed Insights and Google Lighthouse (the source of the PAgeSpeed Insights software.) I've used similar programs like Hummingbird for WordPress that pulls the same data using the same engine, but its really the only game in town as far as I'm concerned.
The others simply do not compare to Squirrly SEO because it is more efficient, accurate, and effective. Squirrly SEO has increased rankings, traffic, and content optimization, which others simply have not been able to do. Moreover, Squirrly SEO operates like a consultant that guides you or tells you what to do, so that improvements can be done. Furthermore, it has much more features than other software.