Poshgirl
I can not say it’s my favourite as I used it a little on MAN - JFK route in Business with BA, and not that great but got me home quick instead of via LHR. I did use Flying Colours for some dashes down to Palma as well, and it was ok for that, as long as you got larger leg room seats. With regards DC8 stretches I did a couple of flights, and never noticed much difference from 707 when tricked out for First , Business etc.
Cheers
Mr Mac