I have never tried a Stennheisser, so cannot comment on that.
I have a David Clark heatset, which I bought nearly 30 years ago, which still serves me very well. I have a David Clark helicopter heatset/helmet which I bought more than 25 years ago, for which I just received extensive warrany assistance from David Clark staff. Nothing was wrong with it, it just needed a wiring change to update it to newer systems.
I could not be more happy with the quality of the David Clark products, and in particular, their excellent after sales (25 years) service!
And the vice head thing, it's what is needed to get the good seal required to keep the noise out. The headsets which don't have a firm grip of your head, probably are not keeping the noise out as well. The alternative is noise cancelling, though even those do not work properly without a good seal around your ears.
I learned to fly in an era which predated the use of headsets, but very quickly became the odd one out by buying and using one. Many pilots senior to me seem to now have hearing problems. Thanks to David Clark quality, I do not!
I highly recommend David Clark products...
Pilot DAR