Here's the thing. I would say, on a technical basis, DSOTM is one of the best albums ever made, and the four band members were right at their peak. But speaking purely on the listening experience I've gone for WYWH.
As far as my taste in music goes, this is probably the toughest album battle I've seen on CRF, as these are my two favourite albums. I'll start by saying that I think The Dark Side Of The Moon fully justifies its reputation as one of the greatest rock albums ever recorded - as has so often been said the flow of the album is superb and it's not short of highlights either. However, I think Wish You Were Here just edges it for me, chiefly because of the magnificent Shine On You Crazy Diamond in its full nine-part glory.