The rise and decline of letters

In this case, value-wise, it would be the letters "Z" and "Q".

Scrabble: Should letter values change?
Laura Gray, BBC News, 14 January 2013

All Scrabble players know that Q and Z are the highest scoring tiles. You can get 10 points for each, in the English language version of the game.

But according to one American researcher, Z really only deserves six points.

And it's not just Z that's under fire. After 75 years of Scrabble, some argue that the current tile values are out of date as certain letters have become more common than they used to be.

Call for controversial word score changes in Scrabble
Richard Allyne, The Telegraph, 15 January 2013 (hat tip: MR)

Among the notable additions are all of these short words which make it easVaier to play Z, Q and X, so even though Q and Z are the highest value letters in Scrabble, they are now much easier to play.

 

So "X" is holding its value, and as noted in the first article, "U" should be gaining.  My guess is that the Spanish ñ (enye) is trying to shoulder its way into American versions.