Fractal design Define R6, although, I like the tempered glass version a lot better AND if you really want good airflow, you're not going to find ANY case that's particularly "silent" or quiet because in order to have great airflow a case also needs to have a free flowing full mesh front panel, which means it's not going to be as quiet since the fans are directly open to the outside of the case and therefore, your ears.
But the R6, and the R5 before it, are EXTREMELY quiet cases if you use the right fans with it.
To be honest, ANY case is VERY quiet if you use the right Noctua fans.
I have a Define S case with a full mesh front panel and a tempered glass side panel, with no noise baffling material, and there are 8 Noctua fans installed. Six 140mm NF-A14 chromax.black.swap fans, one 140mm NF-A14 iPPC industrial 2000RPM black fan and one 40mm NF-A4x20, and at idle it is DEAD SILENT. Even running a full stress test with Prime95 or Realbench, it can BARELY be heard. Sounds about like a room fan running in another room.
If you're willing to buy the right fans, at about 25 bucks a pop, then just about any case is a good choice so long as it supports 140mm fans in all the fan locations. I recommend having 2 or 3 front intake fans, one top rear exhaust fan and one REAR top exhaust fan, for most configurations. There are a lot of cases that only support a 120mm fan in the rear exhaust fan location, so if you choose a case with this limitation, obviously you're going to need a different fan model but that's ok too. Noctua (And a couple of others that aren't quite as good but might be nominally less expensive) makes a good 120mm fan in several different models as well.
Much might also depend on whether you intend to run air cooling for the CPU or are planning to use some form of water cooling such as an All in one closed loop cooler. If you want a quiet build, I recommend going with air. Pump and radiator fan noise CAN be quite annoying if you sensitive to such things.