I just finished a bottle of the Laphroaig Quarter Cask and I often drink the Lagavulin 16. Both are very smoky, quality single malts.
Personally, I find the Laphroaig a little rougher around the edges. It's slightly more medicinal and has a longer finish.
The Lagavulin is slightly smoother, less medicinal, yet more spicy and it has more of a medium-long, but drier finish.
I personally rate the Lagavulin 16 higher than the Laphroaig QC, but it is more expensive and both are good.
I don't claim to be an expert by any means, but hope that helps.
Last edited by San Francisco; 03-21-2011 at 11:05 PM.