In line with Ian, I can not recommend AIG enough. By far the best AI for flightsim and the Australia and New Zealand coverage is in line with the Orbx AUNZ AI coverage, which many payware addons seem to fail miserably at.
They now have their own software to download and install every flightplan and all the necessary AI models and effects outside of the P3D folder which can be found here.
As well as this, another member of the AIG forums developed a tool that can change AI in the sim, like deleting approaching and departing traffic and limiting traffic to save some FPS - this can be found here.
Honestly, having come from UTLive, nothing compares to what AIG have. The only thing that ever came close was the Orbx AI package that only covered Australia and New Zealand. This covers the globe.
