I've used libresprite and generally think it's very nice, but I'd really recommend using GIMP or Krita over it for most pixel art, learning those is useful outside of pixel art
it does not have the ability to draw with higher resolution brushes for subsequent resolution reduction, etc.;
it does not have shader graphs, as in Blender, Pixel Composer, PixelOver;
it is difficult to draw in an indexed palette, unlike PixiEditor,
you can't take 3D renderers and transform them into pixel art, like in PixelOver or Blender,
and there's no bone animation for 2D, like in Spine.
Aseprite is a good editor if you like to paint pixel by pixel every frame without using the advancements and workflows that other style designers and artists use, but calling it the best would be an exaggeration.