I think citizenship is the main factor. If you have dual citizenship, I think you should be given the choice to decide your own nationality. (But you shouldn't be able to flip-flop between nationalities all the time). For example Alex on the rPB tops has French and Finnish citizenship, and lives in Luxembourg, but he chose to be listed as Finnish.

Another good example is Yasu, he wanted to be Polish on the charts because he has some Polish roots but since he has no Polish citizenship and was born and raised Denmark (don't quote me on this, just what I was told), he was put on the the charts as Danish.

In terms of the borders of European tops, I think Israel, Georgia, Armenia etc. shouldn't count as European. They're only in Eurovision because they are part of the European Broadcasting Union, not necessarily geographically part of Europe. Turkey could probably be considered European since part of it is actually in Europe. But who knows, people will definitely disagree with that and there are a lot of points for and against.

And countries like Singapore should obviously not be on American tops just because they have blue line online.

The world is a strange place