For industrial purpose which CAD/CAM software best and why?
Selection and purchase of suitable CAD / CAM software is worked out the same way as any other tool, machine and equipment. First look into if it is capable of functioning within your production / design requirements, then the most important part can your company get a reasonable rate of return on your investment, or in other words will you get back within a reasonable time frame both your purchase cost and productivity costs and improvements that justify the capital you have outlaid for the CAD / CAM software you have purchased. The software may be wonderful from a technical point of view but if it does not make you money its a bad purchase.
Looking at my answer above, I am adding some more detail. When you ask the " What is the best Software " question all you will get is a range of opinions, some will be from persons with knowledge and experience, some with limited experience, some will be from those who have only come across and used only one product, and a few that have used many of the software options available. With such an open question no one will know the exact requirement you have for this software. As I have said a ready, software is like any other component in a production system, you need the most suitable and value for money option that fills your requirement. I have worked for a company that has not looked into all the options, not done their homework, purchased expensive software, based on a staff member having been at school with the salesman. The salesman was looking at maximizing their commission and sold that organization the most expensive option they could talk them into purchasing. A big outlay for a product that was not the best fit for their needs. I have also done work for companies who take the purchase of any tool much more seriously, they do the research, track down information on all possible options and thoroughly investigate that they select software that will do the task required from it and at a cost that does not have a negative effect on profitability.
As engineers we need to take software choice as a serious business, getting a few opinions has some small value but to make an informed decision requires much more effort. With the internet, google and with many software producers allowing potential customers to download demo versions of their products so you can check out a products suitability, don't rely on a few uninformed opinions but approach software choice as an engineer, analyze your requirements, and how they fit in with any possible software product, and then look at purchasing the best option.