The Quadro and Samsung 970 are fairly low power consumption components. They can’t possibly consume more than 200W combined. However, there are numerous variables that are unaccounted for. Drives and other devices are going to draw power too. That’ll increase your overall maximum load.
It would be to your benefit, to future proof your PC, to go for more than you think that you need. For example, if you think that you might be able to get away with a 500W or 600W then definitely go for a 750W instead. PSUs become increasingly less efficient over time and can lose up to 20% of their original output capacity.
While you’re at it, try to go with an 80 Plus Gold or higher - Platinum or Titanium if you can afford it. The higher the rating, the more energy efficient it is. For example, an 80 Plus Bronze is only 85% efficient with a 50% load. However, an 80 Plus Titanium is up to 96% efficient with the same load. Even though it’s only 2% better than the Platinum at that level, it can end up saving you a bunch of money over the course of the product’s lifetime. The more efficient you can afford, the better.
Just keep in mind that, when choosing a new PSU, higher wattage is going to usually also end up running at a higher temp. Newer PSUs tend to have decent fans, heat sinks, and ventilation, but they still run pretty warm. Just make sure that your case has ample air flow and cooling. Tie down those internal cables to provide a clear path for air. Clean out any filters or air vents too. You’ll kill your components if they aren’t cooled properly.
As far as brand goes, Corsair and EVGA are solid brands. They’re generally built very well and provide stable power with little fluctuation. You should expect to pay somewhere in the range of $100-$150 for an 80 Plus Platinum 750W.
I’ve got a 1,300W EVGA in my system. (Necessarily high because I’ve got an i9 12- core, 1080ti, and about 17TB of HDD storage.)