Was it the Daily Prophet?
The Lik O' Rish spiders card with it's wonderful spider printed variants?
The unattainable and excruciatingly rare PearTree leaves card? (mind you... the Peartree had as much screen time in HP as Orc number 165438 in the LOTR movies!)
Come forth and nominate your favourite - the ones with the most nominations will be put into a thread where we can vote for the "best" (or at least most loved) card in the set
I'd like to nominate the
Permission Slip Prop . It (in my opinion) shows Harry looking very sweet and small and reminds us that although we see him as this great wizard with all this great responsibility he's not even allowed outside the school grounds without a signed permission slip (not that he can't get into enough trouble by himself INSIDE the school grounds of course).
It also had some pretty cool variants too

What about everyone else?