I have ZERO background in SEO and am entirely self-taught. My website serves a niche market and is a side job, so not my primary focus. KWFinder was fantastic for easy explanations of why things mattered (i.e. CPC, KD) and free to try. Also, when I did have questions, I got a really quick email chat reply (always lovely.) I cannot speak to how ideal this is for someone more advanced in the industry, but for a small and low budget project it has been perfect.
SE Ranking is on a good track when it comes to rank tracking. It displays a graph of your average position over time which is helpful and it can also help you when it comes to identifying some basic SEO issues with your website. It boasts as an all-around SEO tool, which it definitely isn't because it lacks a link database to be your go-to tool for everything SEO. Its UI is not optimized for ease of use, thus offering sub-par user experience. It has two different interfaces for different SEO tools which, I hope, they can incorporate into one.
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.
All these tools are extremely powerful, and keyword research is just one component of the tools. That said, keyword research using KWFinder, for me, has been most enjoyable out of all of these. It's mostly because of how easy it is to use. The UI is nice to look at, it's just a fun and quick app to use.
SE Ranking was our choice based on the suite of features it offered compared to competitors as well as the # of projects you could manage. From a cost perspective, we feel it provides the most value for your money. Other SEO tools did not offer the lead generation features that SE Ranking offered as part of their monthly plan.
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.