>>5933965Photoshop used to be the best by far in the 90s and early 00s. Now it's good, among a dozen others that are more or less equally as good, with minor differences in specialization.
PS is among the best for customizing brushes, though CSP and Krita are its equal there. PS has the advantage of a wide install base so it has by far the most plugins and user made brush packs for you to play with. It has a lot of options for filters, masks, and vector capabilities. PS does have some disadvantages compared to other packages, even if you forget that PS is way overpriced. Sai runs much faster and more stable. It has no 3D (as far as I know, I may be out of date). CSP and Procreate have 3D to help you out with poses and backgrounds. Krita has more powerful layer hierarchy that lets you apply any number of masks to any number of layers.
Personally I wouldn't use PS because not only is it overpriced, but it depends on Adobe's servers, which have occasionally gone down. Its capabilities make it a good all rounder though I don't see how it could be considered the best. There's now lots of competition.