The could-have-beens
There are so many POVs that could have been great had we gotten them before the characters died, starting with two of the five kings who gave the war its name: Renly Baratheon and Robb Stark. A Renly POV could have given us a clearer idea as to what he wanted to achieve, in addition to providing us more insight into his personal life, a subject the other characters skate around. As for Robb, he and Rickon are the only Stark children not to have POVs. Rickon still has a chance, but Robb does not. It would have been interesting to compare his internal development to Jon’s.
It could also have been interesting to get a Martell or Greyjoy POV earlier in the story. There’s a lack of information about house houses early on, particularly the Martells. Could advance chapters have helped prepare us for the many Ironborn and Dornish POVs in Feast and Dance?
We could say the same thing about characters from Essos, although the books can only have so many POVs before the story starts to feel padded. Still, it’s an interesting thought experiment.