This is an old one, as far as poll-age goes, but bear with me, I just recently discovered these.

So! #1 - Monster Hunter interviews. Almost entirely because of HARRY MOTHERF---IN' DRESDEN OH GOD I LOVE HIM. It is without a doubt the best urban fantasy series out there right now, in my opinion, and I loved seeing him interact with the cast, if briefly. But if it was just that, then it would only be second place or so. I also really enjoyed the other crossovers, specially with Spike being sassy and apparently not-yet-soulful-yet-still-chipped-while-knowing-of-Potentials.
And, of course, the one with the Winchesters and Crowley and Az, which is without a doubt my favorite comic in GND so far. I don't know WHY I love it so much, but it's just hilarious and works on so many levels.

As far as where the rest stack up:
#2 - TIED: Evil League of Evil/Return to Labyrinth due to LUNA!!!! I just...I just love Dr. Horrible, and I loved seeing him and Penny (as a ghost 'cause of course she'd be the only one not getting to be alive in this world (sniff)). Like I said in some other comment, I keep hoping Erik will discover his blog and then they'll jam together! As for Labyrinth, I just find it really clever and interesting writing, utterly beautiful to look at at times, and I just plain love Luna being Luna, which is a huge perk.
#3 - Erik/Mag/Christine/Raoul. I love seeing Erik happy. And it makes my inner Latino giggle at Christine's nigh-jealousy for Mag, even though I know she loves and is happy with Raoul. The soap opera! In our next installment, Erik is PREGNANT. And RAOUL IS THE FATHER. 'Cause, yeah, that's how that works.
#4 - The Time Skip. I will never stop wondering what happened in those 4 pages we missed. It keeps me up at night. ...I bet it involved Coulson scaring Jareth somehow.
#5 - COULSON. Nice guy. See above.
#6 - Cut-short dream. I really surprised myself by having this so far down the list. It's not that I didn't like it, just liked the above more. You really have this strange way to make people seem sexy on-paper. It's wonderful.
#7 - Depressed & Honest Jareth. I love Jareth, and it's totally in-character for him to be mopey. It just happens a little too often in the comics for my tastes. I prefer when he has the slight-upper-hand in a situation and is all aristocratic and pompous (like when he caught Sarah in his room). Now if the poll had said Depressed, Honest & Slightly-but-unnervingly Homicidal Jareth, this would be much higher up in the list. Probably 5, maybe 4.
#8 - Other: ...am I really the only one that think Dr. Frank N. Furter's minicomics deserve a spot here?
#9 - Labyrinth cause of Fail-lessness and drama. Wasn't sure exactly what to make of this one, since I didn't know what Fail-lessness meant specifically, but I said before I love the Labyrinth arc so far for the clever writing, which has almost nearly no drama at all. In fact, it's more of a subversion of drama ("WE HAVE TO FIND MY MANLY JEWELR-" "Accio." "...oh. ...no bonding adventure?") in my opinion, and that's what makes it so good. So this one's the last spot.

Sorry for the essay! Love the work so far.