Re: "I will recommend the SB-5000." - totally agree it is a beast, but man, that price tag is heavy. if you are looking for something more budget friendly but still high performance, you might want to consider the Godox V1-N Round Head Flash. i have been using it on my Z9 and it works pretty well, though you should definitely be careful with the firmware. since the Z9 has no mechanical shutter, some older flashes struggle with sync timing, but the V1 handles it fine after an update. honestly the lithium battery is a lifesaver for long events because it recycles way faster than old school AA batteries. i would suggest being a bit cautious with the plastic mounting foot though, its not quite as tank-like as the nikon stuff. make sure to double check your settings because sometimes the Z9 high speed sync acts a bit funky with third party triggers if they aren't seated perfectly. if you want to save even more, the Godox V860III-N Speedlight is basically the same thing but with a standard head. just my two cents while im scrolling through here.

I will recommend the SB-5000.