I chose the Sapphire RX580 Nitro+ 8GB mainly because of it's bigger cooler.
Fans are dead quiet, even when playing a game for a few hours...
Maybe the blower style cooler is noisier, but since the heat is transferred outside the mac pro, the PCI compartment fan will be more quiet. No idea wich of both options is less annoying 😉
Got my PSU and PCI fans under control now with Macs Fan Control.