What land in the West Bank and Gaza should belong to a new Palestinian state and what should become part of Israel?
This is, of course, a matter of personal opinion. There is no way to objectively decide which lands should go to which side.
My own view on this matter is that all of the West Bank and all of the Gaza Strip should go to the Palestinians. I will admit that I do not know what should be done about East Jerusalem, though I would like to see that go back to the Palestinians as well, though it would be important to allow Israelis access to that area.
I do have some sympathy with the idea that Israel should be able to have as much of the West Bank and Gaza as it likes. After all, these areas were only taken by Israel after Jordan invaded that country during the 6-Day War. From that point of view, the Palestinians have no right to complain since it was their side that instigated that part of the war.
However, Israel has not taken the West Bank as part of its official territory. It has occupied the area but has not tried to annex it. I feel that the Israeli support of settlements in the West Bank is in completely bad faith and is a way to try to take more and more a territory that they officially do not claim. I think that the Palestinian state should include all of the West Bank and of Gaza.