I usually use a passive, but when I did my EASA CPL, borrowed a Bose-X from work. In my opinion, whilst a bit odd at first, the much reduced background noise I was trying to "think through" significantly improved the my learning ability, and saved a significant number of hours of training as I was learning and improving faster.
I then, mostly and happily went back to my passive (which I more recently used happily for my FAA CPL), but I confess I'm thinking at the moment of getting a pair of these, about which I'm hearing good things...
https://www.seht.co.uk/anr
That said, as I'm broadly happy with my passives at the moment (a set of budget Mendelsson HM40s) I'm in no hurry
G