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.
If you have any problems with your rankings or a decrease in ranking position within google it is very good to make an Link Audit with the Link Research Tools. Then you Screen all Links manually and setup your disavow-file easily. With the Link Detox Boost you gain Rankings back so fast. The last time we used it for a client, we got back the rankings within a week to 170 Positions within the Top Ten, even Position 1.
calculates the opportunity or risk of potential links that are not built yet, so you can go only after the good ones
gives you fresh data from 26 link sources and lets you analyze the full backlink profile. Google search console gives you only a sample of your backlink profile.
powerful link prospecting made easy
possibility to connect with Pitchbox (professional outreach tool for link removal and link building campaigns), SEMRUSH, Ahrefs, GSC
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.
LinkResearchTools is much more advanced in analyzing links. Period. All the other mentioned tools have many useful features for SEO but LRT is definitely the way to go for backlink analysis, link building, and competition analysis. They also offer very nice and quality courses for improving SEO knowledge. I already attended one of them and I am very satisfied with the knowledge I gained.