AppFollow is well suited if you only operate in a few app store countries and don't have a high volume of keywords that you are looking to rank for. This is, of course, the free plan. Besides that AppFollow is well suited for communication with other apps - they have an open API and other connections to a ton of third-party analytical tools.
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.
While App Annie is extremely robust and pulls in data from acquisition channels, app stores, and elsewhere, it can be quite overwhelming at times. If you are looking for more simple and just keyword positioning then definitely look at AppFollow. Apart from the two platforms themselves, I've had numerous contact experiences with both AppFollow and App Annie. The winner is definitely AppFollow with a less aggressive approach and a higher willingness to go above and beyond to make sure all questions are answered. With App Annie I was bombarded with a ton of sleazy, sales emails to purchase their product.
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.