If you have very oddly shaped ear canals, or listen for serious lengths of time (>6hr continuous), or consider having a set of custom earmolds made for whatever choice of earbud you prefer. A good earmold blocks more sound than any earplug, the headphones sound better because the ear seal is perfect, and the perfect fit means you never get a sore spot or discomfort even after extended wear. You may find ANC to be totally unnecessary with an earmold (which is also a potential downside, if you need to hear your ambient for safety or for communication like in an office or riding a bike). But to give an idea, I listen with custom earmolds and usually have my device set to the lowest volume, one notch above zero, even in fairly noisy environments like machine shop or airplane cabin. I can wear them for 12hrs straight, zero discomfort, totally forget they're in.
Cost is the obvious downside - audiologist charges 60-100 to make the impressions, then the earmold company charges another 100-200 to make the earmold, and then you still need to buy the earbud to install in the earmold. And then you're "locked" to that earbud - if you ever change brands, you need to make another earmold (no need to do a new impression though, the earmold maker will usually keep your impression on file for X number of years).
Here are some example providers, not a recommendation:
https://www.plugup.com/bluetooth_custom_ear_molds_p/bt.htm
https://www.averysound.com/as.bluetooth_cell_phone_earpieces.html
Again, if you have very oddly shaped ear canals, this is really the best way to go.