I'm relieved not to be the only one who don't know the meaning of "eligible". It seems to be an intersting word if also Americans don't understand it
In my English-German Dictionary it is translated with words like: admissible, bankable, skilled, desirable . . . (if I translate them back to English)
I think in connection with the "who is the the most eligible royal poll" it means something like qualified (like mizzy2006 said).
conclusion: People think that William, Harry, Charlotte and Victoria are "qualified" to be a prince/ss. I have the impression that it is rather a "who is the most LIKED royal" poll
