Best high-end headphones with noice cancellation ...

I know, looked at those as well, but just have the feeling they are much "plastic-like" ... maybe not .. 

I like the Sonys. Fidelity will depend on what you're using them with. Android devices support LDAC, the bluetooth codec with highest data transfer rate. Apple devices do not, nor does Windows. But, the headphones can be used wired.

Would be using them with an iPhone 11 or on an iMac. 

I asked a similar question a few years ago and was convinced by the responses that instead of looking for headphones with active noise cancellation (ANC) that sounded better than my Bose over-ear I was looking to upgrade from that I’d be better off with the passive noise cancellation from a good set of IEMs. IEMs will be much smaller for your carry-on or to tote around town and Shure (for example) advertise 46dB reduction in outside noise levels.
The noise reduction is definitely different from ANC in that it is across the spectrum and all frequencies with good IEMs as opposed to ANC that often works best only with constant background noise (like airplane engines or the lawnmower) but works less for sudden sounds that aren’t constant which instead sound muffled/wrong but definitely get through. 
I ended up with a pair from Campfire Audio and love them, but there are lots of IEMs that will blow away the best ANC headphones for sound quality at the same price. 

If you’re committed to ANC, the Sennheiser Momentum True Wireless 2 are often said to be the best of the ANC IEMs for sound quality if the small and travel-friendly form factor of in-ear is important...haven’t heard them myself.