I'd say the order of comfort generally goes as follows: VS Premium Economy > DL Economy Comfort > DL Economy > VS Economy
If flying in standard economy, I would prefer DL due to the better seating configuration (2-3-2 on DL 763/764 vs. 2-4-2 VS A330/340 or 3-4-3 on VS 744) and more spacious seats (pitch and width are slightly larger on DL than on VS).
One caveat is that the economy seats on the VS 744 upper deck offer a rare chance to fly up top as a coach passenger and are arranged as 3-3.
IFE is very good on both carriers. I can't comment on meal service in Y from personal experience but believe the two are comparable.