Depends on you and how you use the pc.
In general pull configuration works slightly better when fans are run below @ 1200rpm. There's enough vacuum created that the motor housing isn't a factor so the whole surface of the fan area is in play. When fans are run above @ 1500rpm, push is more effective due to higher cfm countering the motor housing loss. Between @ 1200-1500 there's no real difference.
So if you have lower speed fans, you'd be better off with pull. High speed fans, push.
But that's only the math. Location makes a difference too. In pull, the rad comes first, so takes the brunt of any dust in the case. This makes for very easy cleaning as you don't have to remove the fan to clean the dust out of the rad. But, RGB lighting can be a factor, kinda sucks for a top mount to have the RGB buried in between the fan and rad, so push would be better, performance be damned. Same applies for front mount if the case is open access not covered, solid front.
As is, the NZXT H500 can only mount a front aio of 280mm, so half of that becomes a moot point, for non rgb fans I'd go with a pull config for sure. Pc fans have higher static pressure on exhaust than intake, so in pull that'll put more air at the gpu since there's no radiator to diffuse the airflow. Also makes cleaning easier, just pop the front off and hit the rad with a vacuum. No need to take anything apart.