Dont post such hypothetical questions like that. :)
It all depends on your requirements and time to decide which methodology to use..
As far as i know RAD is all about coding directly without proper planning...
Use whatever xyz development methodology you want and come back if you are stuck anywhere in coding..
That's all i can say..
WARNING: THIS IS VERY SIMPLIFIED:
Methodologies split into two main camps - waterfall vs RAD. Waterfall methods are based on sequential processes - get requirements, then design solution, then code, then test etc.
RAD methods are based on building something very quickly then improving it through many iterations.
In my personal experience waterfall methods are generally disasters. They fail because the requirements stage needs the user to help generate a complete and accurate spec - which they never do except in the most trivial of apps. When the user gets the final; system months or years later they typically take one look at them and say "where's X?" or "how do I enter multiple Y's?". The developer says "that wasn't in the spec" and the user says "well, I didn't think about that at the time".
RAD methods (once again: my own personal opinion) work better because the user is involved in something he understands - a working prototype. The user and the developer together converge on a joint understanding of what is required and after enough iterations you have a valid complete app. Object-oriented methods/languages are ideal for RAD because encapsulation and data hiding make it much easier to change things when you iterate.
I always use some kind of RAD, and refuse to take any part in waterfall projects.
Other people's opinions may differ. In the end its up to you.