I just received the P14s today to replace some (very old) Noctua 120mm fans that I had re-used from my old system.
I can't comment on noise comparison as these are 140mm vs 120mm, but on build quality the Noctua fans are so much better. From the vibration pads to wiring sleeves, it looks like a well engineered product. Looking at the fans compared, if installing on a case/radiator I would go for whichever of the two, however if installing on a cooler I'd go for the Noctua as it has anti-vibration padding. Fans on CPU coolers are loosely installed, so there can be some vibration noise where those pads would be useful, but for case mounting where the fans are rigidly attached, not so much.
I have also had exemplary customer service from Noctua (once in 2009 when I struggled to install my cooler, and once last month, when I ordered an AM4 mounting kit for the same cooler I got back in 2009!), so would rather spend my money on them, however on this occasion went for the Arctic's due to availability.