Which is better? JV2 or JV3?

Though the differences between a JV2 and JV3 are minor (refer here), JV2 (Green Star) Performance Solution requires the proposed building to generate 90% or less greenhouse gas emissions than the reference building. However, for JV3 assessment, NCC demands just a small reduction and could be as little as 0.5%. Greenhouse gas emission reduction of 10% as required under JV2 would be more expensive to achieve. We recommend JV3 performance solution for compliance with NCC and JV2 method for the projects that require a Green Star rating.