Are you looking to sell the domains or build a site/business?
If looking to resell the domain then you would of only needed the .com - though this could change depending on what niche you are targeting.
For Brand protection this depends on what markets you are looking to trade in or target - US, UK, Germany, Canada, Australia etc etc then you might need to consider country extensions.....
The rest, well you can't buy them all and most of the time it's not worth it. So .com is the priority followed by the country extensions, dependent on your sales geography. IMO
But again all the above could change depending on budget, growth plans, market competition and other factors.
So.......it's your business (which I know nothing about), do the research and see what is the best fit for your circumstances.