KeywordSpy is appropriate for most Internet Market research companies. I would not suggest it for a corporate marketing department unless it's a company with a very larger budget. This is also not a tool for small freelancers even though there is a free option, to get the best benefit of KeywordSpy it's best to use most of its features and options and this can get pricey.
SE Ranking is a fantastic tool if you are a marketing agency or freelancer looking for a single tool for the majority of your SEO work. It also includes B2B tools like their lead generation widget and white label reports that can help you generate new leads for your business. It would get 10 stars if their database was larger to accommodate research for small geographic areas, but they are always expanding their database so it may just be a matter of time. Research SE Ranking has pricing plans available for every budget.
The support is great but they don't have 24/7 support. And time zones can also be an issue sometimes. On the other hand there are plenty of guides and videos around to get yourself started. I never really needed support for "big" issues. And the help I got was good enough.
Most SEO and market research tools offer what KeywordSpy has but are not as detailed and in one place. Consequently, where you can do everything at KeywordSpy, with other tools you find you have to purchase multiple tools or subscriptions from different providers which also don't integrate with each other. KeywordSpy makes your research easier and more efficient.
SE Ranking is better than Serpstat or MOZ or Ahrefs when it comes to tracking keyword rankings, but it lacks in every other SEO category, such as onsite and offsite SEO metrics, content analysis, etc... It's a good choice for agencies that are interested in tracking keywords for their clients, but other than that it underperforms in every other SEO category.
The website "health" report has allowed us to fix things that Google might find strange or cause us to lose rankings, which has been very helpful.
It's given us more visibility into what exactly our SEO management company is doing and how they are performing, and if things are changing or not. It's very easy to see right from the dashboard.
Being able to see how our competitors stack up against us has helped us know where to improve, what to focus on, and how to be even better.