Well. I don't know about a list.. But I would convey to him how important it is to you to have one. I'd do everything I could do to convince him that you are up to the task of taking care of a snake. It will take quite a bit of responsibility on your part to keep your snake happy and healthy. You have to be prepared to spend money for a vet if something should happen. You need the right equipment which could end up costing more than the snake itself. As far as useless, they def are not companion pets. They wont love you back. You just feed them and they tolerate you. They can live a very long time so you need to be prepared to care for the snake for 20 years or so. They aren't disposable pets and getting rid of one is harder than you think. Craigslist is full of unwanted snakes that end up being neglected because their owners were going though a phase and got bored or frustrated with them when they realize it's more than just tossing a mouse at them once a week. It takes real passion and dedication to provide long term care for a reptile. YOU need to be sure you are ready for it before you can convince your dad to let you have it.