There are many tanks on the market. They all have their advantages and disadvantages from a functionally point of view, along with sustainability and carbon foot print.
Here is some independent reading material to make sure you are making a informed decision.
The first document is a study done on tank selection for drinking water purposes See article Water tank comparisons
In addition here is a good article written by Renew Magazine. https://renew.org.au/renew-magazine/buyers-guides/rainwater-tank-buyers-guide/
The Team at Designer tanks understand each tank has it use and application. We would be happy to discuss your actual needs for your water harvesting plan. Indeed you may have a mix of tanks to achieve your outcome. For example you may feed your roof water into a stainless steel tank and use this water for drinking. The overflow of the stainless tank could then feed into a larger underground concrete tanks for all other water needs around your property. See system design page for more information