There are a lot of research companies emerging in this space. Forrester is an established company that should be considered as part of a set for market research on a topic.
For deeper dives into particular industry solutions, I would seek to complement Forrester's research.
The part of Forrester we used was market research services which were not delivered as part of software at the time. The service received was a portfolio in document/pdf form.
We conducted the research over 5 years ago but find the content still relative today in the area of Governance, Risk, and Compliance platforms. Which gives us trust in the research that was delivered. Review collected by and hosted on G2.com.