I would just go with 48 if you can afford it. I dont know much about AI truth be told, but do know that they are pricey. No matter which model of AI's you get, odds are that they will be quite a bit more expensive in the end than 1 Photon v2+ 48 fixture.
Only thing I will add is this (seeing how you are 16, and probably dont have a lot of disposable income) Only thing you get with AI and Photon light fixtures over Viparspectra unit is extra features like WiFi control, more channels to play with and adjust, dawn/dusk/moon light, appex integration and so on. None of these features will grow your corals any better. They are for your enjoyment and ease of use, but corals dont care about them. For some they are must have features, and thats cool, but for others they are waste of money. Just something to keep in mind, thats all