Honestly, I've owned the Bose QC35 IIs and the 1000XM2s, as they are pretty much the top 2 for BT ANC Headphones. I liked both. It was a toss up, truly, but I ended up keeping the Bose, simply for these 2 reasons:
1. The Bose, even though the sound quality was not a good as the Sonys, were far more comfortable. They are lighter, the ear cups are bigger, and the fit around the head better. For my main purposes, which was extended sessions (usually on flights or travel), comfort was far more important than sound quality, especially since I'm using the ANC to sleep, rest, etc.
2. The Bose has a ton of aftermarket ear cups for when the ear pads inevitably wear out. I know you can get earpads from Sony, but it's not as easy to do as the Bose.
That being said, the 1000XM3s have addressed the comfort issue, and with their superior ANC and sound quality, as well as the plethora of features not available on the Bose, I'm going with the Sony. Build quality-wise, as well as the case/packaging, Sony also wins here. I think it's worth the $50 upgrade.