Not really a Meshify, but similar. I went from an Arc Midi R2 to a Define R6, while keeping the same components and layout (4790 w/ Cryorig M9i, 1070ti on both stock blower cooler and a Raijintek Morpheus, 3 Phanteks F140MP as 2 intakes and 1 exhaust). And honestly the difference was next to nothing, mainly because I have my own set fan curves, and had to crank the fans a couple hundred rpm higher to keep the same temperatures. There was a slight decrease in noise from my mechanical hdd (emphasys on "slight"), but that's about it. And take into account I live on a rural area that's dead silent, so any tiny sound is noticeable.
I reckon the large dB differences are mainly reported by the "install and forget" crowd, but if you're willing to do some tweaking, any case can be made silent, it's all about the components themselves and how quiet they are. I for one can tell you that next time I will not be actively searching for a dampened case, even the case quality itself plays a larger role in sound dampening (such as using thicker steel panels).
Tl,dr: just pick whichever one you prefer, you can make the Meshify just as silent because you can set the fans to run slower.