The Too human video where the staff act like a street gang threatening video game reviewers was always one my favorites. The Jeff Christmas special where he makes marshmallow treats, while hiding being a pretentious douchebag, or the one where he is an obsessed video game collector and Ryan tries to get him help... good times.
Ya, Derek has been doing it for years so technically if you want a best of for the site, start at #1 of his Best Of Giant Bomb series and work your way down. They're good. You won't regret watching them.