So just bought QC35 in black. Listening to Total Belief by Malcolm Middleton on Tidal HiFi on an iPhone 6 Plus, and very happy. Loads of space, complex acoustic guitar shining through no problem. You can hear his fingers on the strings no problem, which is always a good test.
However, my acid test for new headphones is Fallout by the Devin Townsend Project - massively layered and heavy. QC35s struggled a bit here and sounded muddy. All round I'm not sure they're tuned all that well for the heavy stuff, maybe the mids are too recessed, but for everything else it's pretty good. I don't get the sibilance others do, might just be my ears.
I haven't listened to QC25s, but I'd say these are a little more bassy than my QC15s and a little bit less tight. But it's only hour 2 of listening, so I'll burn them in some more.
Comfort - brilliant. ANC - just as good as the QC15s.
My big point of comparison is on-ear Sennheiser Momentum Wireless 2.0. I think the sound on the Sennies is much more forward and much more engaging to listen to. Heavy stuff in particular is just more enjoyable (DTP again, melodic death stuff like Moonsorrow or metalcore like Lacuna Coil and Killswitch Engage). However! The clamping on the Sennies is really strong and can get pretty uncomfortable if you're wearing your Gregory Pecks. I got the late version which should have sorted the Bluetooth glitches, but I've found it's far from perfect. Wind is a big issue on phone calls (haven't tested the Bose for this yet). And the wee multifunction joystick type thing on the Sennheisers is a royal pain in the ass - the 3-button thing on the Bose is much better.
Overall I'm just a wee bit disappointed in the sound, but hopefully it'll open out once they're burned in. But as a regular plane/train jockey there's no question that the QC35s will be my constant companion, probably until some scrote spots them, hits me over the head and nicks them. I had planned to sell the Sennheisers on, but just not sure now, might keep them for office listening...
