It won't be much helpfull, but I'd say that as long as those lenses are around same price tag it doesn't really matter if you'd chose Tamron or Sigma, the difference between them won't be significant, and honestly I don't think that there'll be a difference at all.

As for the focal lenght, I strongly recommend something like 24-70 or even 24-105, not only for cabin photos. On my recent trip to LHR I took most of my photos with 24-105, because bigger aircraft didn't fit in 100-400mm focal range