Premise: it's not really my field, but the short answer is Blender and the long answer, well, it's probably Blender, with some considerations.
Blender isn't really user-friendly when it comes to things that aren't 3D modelling, and many people don't even know it can do video editing, compositing, animation, post-production as well as a lot of other stuff (physics simulation, motion tracking, videogames, etc.), so for your average user who wants something easier to use it's probably not a good suggestion. On GNU/Linux we tend to use different programs for different things. Kdenlive is an excellent video editor, for example, and Natron is great at node-based compositing. OpenShot and Cinelerra do both video editing and compositing, and perhaps it'd be best to recommend one of them. Now, if animation is also involved then things might get a bit more complex. Synfig and OpenToonz (soon) are excellent at 2D animation, and Blender is of course the best at 3D animation. So, yes, Blender covers all bases, and has pretty good documentation, but it looks and feels like a 3D program. Too bad that they didn't find a way to better separate its countless functionalities. If your target is big studios, then Blender. If not, well, it depends, but I would say either Kdenlive, OpenShot or Cinelerra (experts, please aid me here!).
