The longtail cast on is the best all-purpose cast on: it’s stretchy, but not too stretchy; it’s firm yet flexible; it lays flat and looks pretty. What’s not to love? When in doubt, use the longtail cast on.
The only possible downside is that it’s a little tricky to do at first. It involves a bit of hand gymnastics. But if you break down the steps into smaller actions, it’s pretty easy to do. And once you get the hang of it, it’s the only cast on you’ll want to use.