Servlet Vs Creating a custom plugin

Hi,

My use case is the following. I need to automatically assign new daily batch of tasks to workers. Each task, worker has a set of skills. The task's skills must match the worker's. 

Additionally, the algorithm must assign/distribute tasks as equally as possible. 

I have come up with a way to do this by reducing this to a graph/flow problem.

Problem is, it is super hard/impossible to implement this in an expression rule. As such, I want to develop a custom function in appian in Java. 

Which way is better to this, via Servlet or custom plugin? 

Thank you,