The 753s are not that old and they are well maintained inside. I'm not sure that apparent age would differ inside.

The 739 is most likely to have LiveTV on it but no guarantees as only the 73Es are actually fully configured (and nothing is showing right now pending the repairs).

The food thing is very much a personal decision. I generally like the lunch/dinner meals better than the breakfasts but others might disagree. The difference is more pronounced on transcon flights but I'm guessing that isn't what you're looking at based on the 753.

What is the route? That would help us give you more information.