I don't think, it is good idea to think about language and framework first than domain.
If it is prototype or just proof of concept then it is better to use good framework that helps to build quick prototype. May be Django or RoR is best choice if you already know it. But if you have some problem with exiting system like improve system performance or scalability issue then you could think about something else.
In the end, to me need to understand problem first then framework or language but not vice versa.
This is very common situation for most of the people and it is also general for all fields. Many colleague around me who are also not interested about their daily work. Mind set is important factor to do something. Just sharing a video with you....
https://www.udacity.com/course/deep-learning--ud730