If it is really ww3 probably no where safe due to nuclear winter effect.

If you are speaking of a nuclear confrontation, nowhere is safe.

You might live longer if you are in the Southern Hemisphere but you can expect rampant starvation, disease and malnutrition.

And when I say live longer, I mean a couple of years at most.

New Zealand. But it may not be remote enough. Below is a diagram of idealized air circulation around the globe. Presumably most of the bombs will fall in the northern hemisphere, so deadly radiation will spread around that hemisphere pretty quickly.

Fewer targets in the southern hemisphere, plus the intertropical zone is a bit of a barrier, so less initial radiation there. Safer but I have no idea if it's safe enough.

Australia is an old continent; soils are much less fertile than newer volcanic New Zealand.

Greenland lol

If nukes are used unilaterally there is no safe place

I say the US

Radiation and nuclear winter will take over the planet. Nothing will survive.

There's no WWIII. The destruction will be vast and the poverty will be crushing, because that's the politics of the West!
I think you would have to be interested in stopping the war and sustaining peace to find safety. You're never going to be part of the peace on earth we need! Save yourself? Impossible.

The answer will literally always be Switzerland.

The US.

Where the first bomb falls. I would live there very fleetingly.
The real war will be with the aftereffects. I would choose to avoid that.

Some big city center. I'd rather be vaporized in an instant, maybe without even realizing, than starving anywhere distant from the heat