adobe illustrator or corel draw?

I would personally say Illustrator since it's a popular tool to know, but if you plan on doing any sort of printing (like T-shirts, or specialized materials like holographic films and the like) or engraving, you should (also) learn CorelDraw since a lot of industry printers specifically use that. Ultimately they're not too different conceptually and it's not too bad to go between the two.