which is the most popular modelling software used?
Here is a list of some of the top choices:
Though, your answer is not black or white. It depends what type of modeling or plugins you are going to be working with. While one software may excel in some aspects, it may be lacking in other needs you have. The best choice would be to ask yourself what it is you will be doing, and work from there.
Many people around the site are very knowledgeable and would be more than glad to help if you wanted to narrow it down to a few software choices. Some of the major players in the game for modeling would be Creo, Autodesk, Solidworks... but on the opposite side, those choices may not be suited for the tasks you are needing.