What do you mean with re-sale? That it is easier to sell them if you do not like them?
I mush prefer the sound of the Senny but the Parrot are very good too and depending on what you listen my be even better, and you can configure them (surround, EQ, and different kind of ANC).
On flights you can use them wired and still have ANC (although not the other effects). I mean, you can always use them wired, but I said on flights because you are sit and the wire is not a problem.
I did not read any direct comparison of the two. I have the impression that somebody wrote that the Parrot have better ANC. Not sure though.
Are you allowed to use BT on flights? If not, you should ask around (probably in the thread of the Senny) if they keep ANC when wired.