Damn Karl - I was going to vote the Drew network 'PSA proposal' and 'original Hotforwords fan' because I relate to them so much! (and I DO!)
At GREAT RISK of appearing a total KISS ASS - my first choices are actually Marina's above because I see all four as masterpieces of Scripting, Performance, Message, and Editing - really well honed examples of craft, wit, production, etc.
To take it to a more personal level, I concur with Hs4mm on 'Grandfather's Clock' because the performance and singing is very cute and endearing. http://www.youtube.com/watch?v=Q5XR6DAuIOc
I also loved http://www.hotforwords.com/2008/08/06/ukulele-the-next-big-thing/ for the clever scripting.
Another favorite is Pedigree because I found the origin most interesting and surprising. http://www.hotforwords.com/2008/04/13/pedigree/
I really think that the question is a little broad. My answer kind of depends on what you want to do with the results?
The body of work is so broad that there is really something to like in every one so it's almost like the Academy Awards where there are LOTS of winners for various categories.
I'm guessing you want to feature your 'Best' on the homepage in anticipation of all the new viewers who will be flooding in to HFW.com shortly - once they come here, they need to know where to start and get 'hooked'? That was sort of a problem for me as a 'N00b' as there is so much to choose from...
You have my and other's personal Fav's here - and of course you can't go wrong with listing your highest viewed also as they've been proven to be broad favorites.
Maybe do a 'Top Ten' or something mixing highest viewed with those you are most proud of and suggestions here? You could rotate them too...
OK - I have to go now and clean off my nose. ;=)