The most important thing is not to buy a no name Power supply.
Popular brands are BeQuiet, Corsair, Seasonic, Silverstone, Corsair, MSI, Phanteks, Antec, Sharkoon, Gigabyte…
You definitely should not save too much money at this part since it is related to safety. Especially if you live in a Country with a bad electricity network, since too high voltage can not only kill your PC, it can also kill you in the worst case.
The second most significant thing is, you need a Power supply which supports enough Wattage. Here is a calculator to find out, how much you require.
When it comes to rendering, efficiency can become essential since rendering means using a lot of power over a longer period of time.
To certify the efficiency of a Power supply there is the 80 PLUS certification, the higher the certification the higher the percentage of the energy the power supply pulls out the wall it will pass along to the computer components.
Which can be translated to the higher the 80 PLUS certification, the lower the energy bill will be.
If it makes sense for to buy a Power supply with a higher certification is something you can roughly calculate.