I keep seeing lots of debates about what program should be used for what.
I’m not claiming this chart I made is gospel, but it should give a pretty good idea on what the strengths are of each particular program are based on some basic needs and parameters.
This chart should also help you determine what program is best to buy if you’re looking to purchase one for things you want to do. For instance, SAI is cheap and can do most drawing/painting needs, but not type or design. Photoshop is an all-around great performer, but is the most expensive program of the lot. Manga Studio can handle more things than SAI, but only about averagely so. Hope this makes sense of things for you!
(Of course, your mileage may vary on these ratings.)
By the way, this chart is totally a rip on the old Speed/Accel. chart in the Super Mario Kart instruction manual. (See page 25.)