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.
SEOGadget is ideal when using vendors like Moz and Majestic for analysis of your backlinks. It is not the tool to use if you need to gain more backlinks or want to increase your backlink. It can help you edit your backlink profile and understand where the links come from. It is probably ideal for in-house teams studying larger sites with lots of links and trying to understand their link partners, or an agency/freelancer that needs to import data from multiple sources to help clients with link profiles. It is not the tool to target new link opportunities, but with some ingenuity you could probably use it for this if you an access your competitor data. It's also good for anchor analysis which is something few teams really look into.
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.
This includes more data and makes backlink analysis easier because you don't have to build sheets and tables from scratch. While it doesn't directly compare (it uses some of these services) it is better suited for the custom analysis of data and that is a big help when you do a lot of data manipulation. It's easier and more streamlined than Knime, and Knime does not allow you to import directly from Moz or Majestic so a step is saved here. It can't do as much as Knime but most of the things you want to do it can do, and you can do them faster.
It is hard to quantify this realistically but it does save time and that is big
Importing data is a time suck, so the only real advantage here is the ability to do two or three imports instantly without downloading and visiting three sites, this could be expanded for even more ROI
We haven't had any negative impacts as this is mainly a time saver