While a corporate experience might be beneficial for your first professional experience, I believe a startup is definitely more beneficial when taking your first steps. As you develop your skills, you have the opportunity to work in every department. This might not be possible in a corporate environment. In a startup, you can master the project as a whole, whereas in a corporate environment, you`re usually only interested in a specific part of the product, so you don`t have much insight into what goes on. Similarly, in coding, while in a startup, you might be able to handle the front-end, back-end, and system aspects, this is less common in a corporate environment. You might only focus on the front-end, back-end, or system aspects.