the word "best" is hard to describe because it means something different to everybody.
To one person, the best software is easy to use (which usually means it has limited features)
Another person thinks "best" means so many features that you need tutorials in order to use it, but once you know how to use it you can do ANYTHING.
If your idea of BEST is closer to the second definition, I'd recommend HITFILM. It has a free version and a paid version, but even the free version is very powerful. Neither version is particularly easy to use but both versions are capable of doing just about anything that can be done by a high-end video editing /compositing program. (special effects/layering/green screen, particle generation etc)
if "BEST" = free:
https://fxhome.com/hitfilm-expressif "BEST" = better than free:
https://fxhome.com/storeif you want to see videos showing the kind of effects you can get from this software, here's a link to their YouTUBE page:
https://www.youtube.com/user/FXhomeHitFilm