It was a toss up between SoPW and Meditations, but Seekers has proven to be most usefull to me, so I'll have to throw my vote there.
Of course, Super Search should've been a choice too, it's saved me sooo many times.
It's just a matter of asking yourself which section of the web site would be most difficult to live without. The Chatterbox is fun and occasionally useful, but all the really useful stuff is taken care of in SoPW, and I wouldn't consider this Perlmonks if SoPW were missing. I could live without the Chatterbox if I had to.
EDIT: And I really don't know why so many people voted for Meditations.
Obfuscated Code has lost of gems, and you can even learn things from some of them, but I finally chose Meditations because obfuscations would exist even without this section of the monastery, but it would be impossible to gather so many interesting writeups about perl if this section didn't exist.
Well, I'm late to the party because of my sojourn in EU, but I am one who votes for Meditations. Yes, I love the content and helpful exposure of SoPW (learn something new every day!) and I'm becoming CB-addicted, but Meditations brings me a chance to read other peoples' thoughts on many subjects and also to spout a few of my own. I really need a few moments every day to divert myself, and Meditations does that admirably.
One other section that should have been included, however, which would have topped M, is Saints in our Book. All hail the incredibly helpful guys & gals who make PM what it is!!!