I use many different slicers, as it is up to the user - me to determine which one works best for my 3D Printers...

So guess you would like me to tell you what I have determined was best for my uses.

In alphabetical order for free slicers was.

Cura *
IdeaMaker
Matter Control
Prusa slicer *

The two best in my opinion were Cura and Prusa Slicer.
The thing is that I still use Cura 15.04.6 it is great for a quick slice with no special options.
Though Cura's newer version have plenty of option for better print quality Prusa slicer out preforms all slicer I have used.

In my opinion Prusa Slicer 2.4.1 Standalone works so well it could be placed as completion with any slicer you would purchase.
An with the Prusa's programming group working constantly on this slicer it will only get better with age...