What’s your take on SaaS tools for KDP authors—like Publisher Rocket, KDSpy, Kindlepreneur’s free tools, Book Bolt, Helium 10, Merch Informer, Jungle Scout, K-Lytics, and DataDive?

Which ones have actually helped you with niche/keyword research, competition analysis, or category selection? What features do you wish they had, or what would improve your workflow as a writer/publisher? Community insights and honest reviews appreciated—let’s help each other choose the best toolkit!