Today I just randomly checked to see which episodes of GeekNights are the most downloaded of all time. I don't know if the stats can be trusted completely. Libsyn changed their counting methods in May 2010. Also in October of 2013 there was a drastic reduction our download numbers across the board. Any episodes posted before then will have an unfair benefit. Lastly, counting total downloads gives a bias towards older episodes which have a longer long tail.
So, to be fair, here are two lists. One list is just the most downloaded all time. The other only includes shows since October 6, 2013 when the stats drastically changed.
ALL TIME top 10
20120507 - Web Vulnerabilities
20071226 - Batman: The Dark Knight Returns
20120509 - Once Popular Anime and "The Churn"
20120813 - Paying for Stuff
20120702 - Hardware Lockdown and Secure Boot
20120618 - Laptops in 2012
20120626 - Cards Against Humanity and Real Money Auction Houses
20120325 - Tech News Roundup March 2012
20111219 - Software Development Methodologies
20120314 - Order of the Stick
It's worth noting that the Dark Night Returns episode is only 3 downloads behind the web vulnerabilities episode. And that the web vulnerabilities episode has only one download in the past 3 months. Batman has 16 in October, 12 in November, and 2 already in December. It's gonna be number one really soon.
Where the other metrics show some unexpected episodes, this looks most like what you would guess to actually be the most popular episodes of GeekNights.
And just in the interest of fairness, here is the same list with a less aggressive date cut-off. It includes episodes that are clearly receiving some benefit of new-ness, but have significantly more staying power than their contemporaries.