Other than Ukraine?
Simples, ZPP is on Ukrainian territory and Ukraine is well-acquainted with nuclear disasters. If something was to happen that went seriously wrong and released radiation Ukraine would be living with the long term aftermath. Russia, on the other hand, has a large safety buffer since the border is about 200km away.
To be honest, like a lot of things in this war, the ZPP situation is long on claims and short on verifiable facts. Both sides have a vested interest in making the other look bad and ZPP integrity, as it concerns a nuclear plant, is a good way to seed FUD (Fear Uncertainty and Doubt), especially to European countries.
Still, in the lack of definitive info, if deliberate targeting is happening, common sense would indicate that:
if there is actual unprovoked shelling of the ZPP, Ukraine has the most to lose.
if there is counter battery fire, from Ukraine to the ZPP, Russia can simply avoid it by demilitarizing the immediate surroundings as it has been asked to do.
Finally, Russia holds the area and has yet to allow inspectors in (a team is supposed to be going in, as of Aug 29th, with shelling reports dating back from July 16th). Why all the foot-dragging if Ukraine is at fault? Seems like an easy win.
About that foot-dragging, and the lack of hard facts, here's the BBC write up for the announced inspection, 6 weeks after first shelling reports:
Ukraine and Russia blamed each other for strikes that caused the damage. The BBC was not able to independently verify which side was responsible.
Russia's military took over the plant in early March, but it is still being operated by Ukrainian staff under difficult conditions.
The Kremlin had previously signalled that it would only allow international inspectors to visit the complex so the IAEA's visit will mark an important moment in being able to verify what is happening on the ground.
Ukraine had feared an IAEA mission to Zaporizhzhia would legitimise the Russian occupation of the nuclear plant, before finally backing a visit.
i.e. Ukraine is also playing to the gallery. But, again, who has the most to lose in case of radiation leaks?
Last, ZPP is on the east side of the river, at a very wide location. It doesn't have to be "defended" by Russia. And Ukraine has no reason to shoot at it in order to weaken the defenders capable of contesting the crossing - they won't be crossing there. Might be, at most, that Ukraine is targeting Russian troops and ammo using the plant as a hostage shield. IF so, that's a risk they probably shouldn't be taking, but "good Russia" could always not put its troops there.
Honestly, it's one of those things where we won't be knowing until we have harder info and neither party can be trusted not to engage in propaganda (it's wartime). However we can look at the wider patterns of behavior in this war to see who is the least credible of the two, which country tends not care overmuch about collateral damage and which country tends be less than entirely truthful.