You asked whether one should use OOP or FP to implement a system.

I can answer that, and did in the past, as I have done projects in both OOP and FP. But before I answer, I ask follow-up question about the system itself, and I will be giving lots of "it depends" and conditions.

There is no quick and dirty rule that will apply to any situation, and it's definitely not something I can teach in a message board.