Bought the QC Ultra 2 and the Momentum 5 to compare and kept the Bose. Finds the highs and mids crisp and detailed with a smooth, punchy low end, better soundstage and separation, slightly better noise cancelling and by far the best comfort; battery life is about half the Momentum's. Got an open-box pair for $310 and isn't sure it's worth $450.
“The Bose are so much lighter and don't clamp nearly as hard. They are the most comfortable headphones I've ever worn by a mile, it's like wearing a pillow on your head.”