Almost never the expensive ones. The pattern is consistent enough that it is worth stating plainly.
Before selling, the work that pays back is the work that removes objections. The work that rarely pays back is the work that adds features.
A buyer deciding between two homes is not adding up improvements. They are noticing what is wrong. Fixing what is wrong widens your buyer pool; adding something new mostly appeals to the subset who wanted that thing.
The test is not "would this look better?" It is "is the market likely to pay me back for this?" Those are different questions and only the second one matters six weeks before listing.
What is worth doing depends on your specific home, its price bracket, and what comparable homes are offering. A house where every competitor has updated flooring is a different situation from one where none have.
That assessment is free and takes an hour. Doing it after the renovation is considerably more expensive.