LOL, I hear you, but keep in mind, many fish you might like may require different substrate, plants/no plants, caves, etc, so it's a good idea to at least have an idea what you want.
My goldfish tanks are different from my Amazon tank, from my community tank, from my brackish tank...... Different substrate, decor, plants, driftwood.... Most fish will do fine in a tank with common gravel etc so it's not like it's life or death, but it's much more satisfying knowing from the outset what is needed than having to bulldoze everything when you suddenly choose a gottahaveit fish which needs something you don't have or can't live with something you've already got.