Think I have to vote for the 21yo Portwood. But based on the single dram of 15yo old I have had, I think this would have been the favourite if I had had a chance to sample it more extensively. (Still need to finish a few bottles, before opening more.
That said, I enjoy the DW a lot and the 10yo is a cracking dram also....
Heck - if I could vote "Every one" I think that would be the option for me - Balvenie is just a very good dram IMHO.