The Bose QuietComfort 35 II is arguably still the most comfortable pair of noise-canceling headphones you can buy. Released in the summer of 2018, you can think of the QuietComfort 35 II as simplified, less sophisticated and more affordable version of the new Headphones 700. The lack the transparency mode, superior call quality, USB-C charging port and on-ear gesture controls, but they still boast really impressive noise-canceling skills. The also have the tradional foldable design — it folds more compactly — that many travelers really like.
The iPhone will drive the headphone fine and make a very nice sound, but the amp will make a big improvement in harmonic extension and soundstage. Use the amp whenever possible. Both Headfonia and I concur that the E07k is a great amp, and probably the best thing you can get for up to twice the price. I’m familiar only with the E07k, the E17, and the E12. I think the E07k beats the E17 (and both are also USB DACs), while the E12 is just an amp, and has a darker sound but with more power for inefficient headphones. The Philips is not inefficient.
However, the Bose 700 earphones have a much slimmer profile when folded up, and they have a few updated elements, including more integration with digital assistants, touch controls, and sensors for Bose’s “augmented reality” apps. Bose has kept some of the best-loved features from its older models as well, such as adjustable levels of noise cancellation, a monitoring mode to let in sound from your environment, and an advertised 20-hour battery life. According to Bose, call quality is improved as well, though CR doesn’t test call quality in headphones.
LDAC is a strange family of codecs, not merely because they’re the only codecs that really attempt the hi-res thing, but because they have perplexing issues with common phones. For example, the bitrate defaults are wildly different from phone to phone. The Samsung Galaxy Note 8 and LG V30 both default to 660kbps, and the Google Pixel 3 defaults to the lesser 330kbps. However, the noise present with every LDAC connection is far greater than it is with a regular old 3.5mm headphone jack.
Released in 2017, the Bose QuietComfort 35 (Series I) are essentially the exact same headphones as the Series II. They have the same design, feel, sound quality and noise-canceling skills. The difference is that the Series I don’t have Google Assistant built-in and a dedicated button on the left ear cup to activate it. If you don’t care about talking to a virtual assistant while wearing your headphones, which allows you to play/pause music or skip tracks via a verbal command, then Series I or Series II shouldn’t matter to you. The catch is that the Series I is more difficult to find online and they aren’t usually that much cheaper than the Series II.

Over-ear and on-ear headphones effectively block out outside sounds, allowing you to hear your music or whatever else you're listening to crisply and without distraction. Over-ear headphones are sometimes known as full-size headphones because they completely envelop the wearer's ear. This results in what's known as passive noise reduction, which makes these some of the most-preferred headphones available. The only drawback is that your ears and the skin around your ears can get warm and sweaty. These are usually the heaviest type of headphones.