I say Egypt because they pretended to want peace and accomplished what no other Arab country could do. They stole land bigger than the entire rest of the State of Israel.
One interesting thing about Egypt is that they have a big tourism industry that is directly related to Israel. Most of the people that visit Israel are people who have read the Bible and the story of Exodus.
Actually, if the Temple were rebuilt and the amount of tourists multiplied vastly, I could see Egypt as being a potential ally simply because of the wealth that could overflow to them from 10's of millions of people coming to the Temple every year. I could be completely wrong though, maybe there is a conflict of national pride and maybe there is too much anti-Israel sentiment.
However I have done some research about their hotel industry and they have a lot of beautiful resorts in the Sinai which need high paying guests. I think some of the Egyptians, particularly business owners might be happy to see peace in the region because it would put more $ in their pockets. It is interesting to look at and I can provide more information if anyone is interested.