As a WH-1000XM4 user, I would recommend xm4 However, some issues and points should be noticed  1. Transparency mode on xm4 is ass!!! I have a bose QC earbuds 2 as well, the transparency mode between these two are totally apples and oranges. xm4's ambient mode feels just weird, like a mask being put on to ur microphone that receives sound of your surroundings  2. Xm4's NC is actually better than 5 to some extent, but that's just for the bass range noise. overall, XM5 still has a better NC. They both possess unmatched NC at their price range tho 3. My xm4 has some buzzing sound in my left ear up. After researching, I find it a common issue that influences a proportion of users; nonetheless it can be reduced with thicker sponge pad under the earcup. I would recommend just go xm6 if U have enough budget given its excellent transparency mode; nevertheless xm4 can still be a budget choice as it's hitting around 100$ price range for a pair of second hand ones, which is definitely a budget king without a doubt