My preference order is:
1. China. If collecting is not your forte, then open up the bookcases at the base camp when you arrive (there are two) and select "take all" to get them. Also put the stereo in your inventory. Sell them all
once you get home to get around $20,000. They have no value in China, but when home, they can be up to $2,000 each!
2. France. Simply because it's a visually appealing country. I like countries like that.
3. Egypt. When I do get there, it's only to get the Eyes of Horus (allow you to teleport between the two).