I've never had the Lagavulin 25yo. After checking the tasting notes of the Malt Maniacs and other reviews I stayed away from purchasing a bottle. It appears Lagavulin 23yo (Murray McDavid Mission) is a good buy but I've never seen it anywhere for purchase over the Internet.
The Whisky Exchange had some Ardbeg 29yo Douglas Laing bottlings for around £80 which I understand to be some of the best expressions of Ardbeg. I was just about to purchase 2 bottles... they're gone now
Note: I edited my review of Lagavulin 12CS. Lagavulin 12CS is not dryer then Ardbeg 10yo... it's a bit sweeter by a hair. Still my favorite! Lagavulin 12CS has some traces of Laphroaig sweetness and character.
It's a shame Laphroaig has no trace of Lagavulin aside from peat. I'm tempted to mix all three (Ardbeg, Lagavulin and Laphroaig) for personal consumption