There is no one program that will do everything. Adobe applications are professional level tools designed to be used together.
That’s why they are sold together in suites. That said, if you only want to buy one application you’d probably be best off with Illustrator.
Keep in mind, however, that these applications do have quite a learning curve and that buying only one is like a carpenter only have a saw with no hammers, screwdrivers or other tools.