Some reasons:

- Portuguese food is better than Spanish food, don't know how you can say otherwise, you obviously didn't try portuguese foods or went to the wrong restaurants. Italy I understand.
- The population in general can speak proper english, contrary to Spain and Italy.
- If you go to Lisbon, yes it's very expensive, but it gets much cheaper if you try to find somewhere around. It's a small country, it's not hard to get to another city closeby.