Which has better noise cancellation?

The Momentum 4. Its adaptive ANC handles low rumble and voices more cleanly, and Transparency Mode is adjustable. The JBL cancels well for its class but lets more through.

Which is better for long flights?

The Momentum 4 for quiet and comfort over hours, with 60 hours of ANC play time. The JBL lasts longer with ANC off and is lighter, so it suits people who want minimal weight.

The Momentum 4. It has a larger driver, aptX Adaptive and a detailed, balanced tuning. The JBL leans on Pure Bass, which is fun but less refined.

Is the JBL worth stepping up to over the Sennheiser?

Only if battery life, weight and Bluetooth 5.3 matter more than sound and ANC. On audio and noise cancellation the Sennheiser is the upgrade.

Do either work with a cable?

Yes. Both take a 3.5mm cable, and the Momentum 4 also has a 2.5mm jack. Neither has water resistance.

Which is better for calls?

The Momentum 4. Its four beamforming microphones with wind suppression handle calls better. The JBL uses VoiceAware and buttons, which is fine indoors.

Sennheiser Momentum 4 vs JBL Tune 770NC

The Momentum 4 is the better headphone for sound quality, noise cancellation and call clarity, and owners rate it higher. The JBL Tune 770NC wins on battery, lighter weight and Bluetooth 5.3 with LE Audio. Buy the Sennheiser if audio matters most and you want aptX and a strong app; buy the JBL if you want long play time and a light, simple headphone. Neither has water resistance.

Choose the Sennheiser Momentum 4 if you want the better-sounding, better-cancelling headphone with aptX Adaptive, multipoint and a deeper app.
Choose the JBL Tune 770NC if you want the longest battery life, a lighter fit and Bluetooth 5.3 with LE Audio.

Prices

Sennheiser Momentum 4: $199.95 at Amazon (last seen Nov 13)
JBL Tune 770NC: $55.00 at eBay (last seen Nov 9)
Difference: the JBL Tune 770NC is $144.95 cheaper than the Sennheiser Momentum 4 at the latest prices (Nov 9 and Nov 13)