It all depends on what exactly you are planning to do and what you want to learn for which reason.
Photoshop and Sketchbook Pro are a completely different thing.
CorelDRAW does broadly the same thing as Illustrator. It's a vector application. It has some layout capabilities which Illustrator doesn't have.
Do you want to do vector things or do you want to do pixel things? Which pixel things? Editing photos or painting? You will need to learn not only the software they use, but the trade as well.
Which goal do you have in mind? Do you want to get employed? Then you want to learn the software they use at the places you want to get enployed.
And so on.