Geometry: An algorithm to select the most important vehicles in the traffic relative to the main vehicle?

I have the following data about the surrounding vehicles and the main vehicle(let call it E-vehicle): X,Y,Z in earth co-ordinates Velocity Yaw angle Pitch angle

I need to make use of these variables and write an algorithm to select the most important vehicles relative to ego vehicle. Example: To select the 10 most important vehicles from the 100 available in the traffic.

I have an algorithm which uses the distance between these surrounding vehicles and the ego vehicle and selects the nearest ones. However, this is not an efficient algorithm since it can also take into account the parked vehicles which might not be that important when compared a vehicle which is approaching the E-vehicle but is a little far away.

Any ideas on how I can use these variables to write a better algorithm would be appreciated.