I was pretty sad when TF2 moved to quick play/matchmaking. TF2 is by far my most-played game, sitting around 2,000 hours, and virtually all of that took place on a skial.com badwater server or the No Heroes Badwater/Goldrush server. Just to be loosely part of a community, where you'd recognize the same names over and over, maybe even Steam friend up with a few folks whose jib you like the cut of, and the fact that a lot of the time, you'd have two teams that really knew what they were doing.
Defending the roof on that second badwater point with 2-3 engies and pyros doing constant spy checks when they're not airblasting enemy ubers, just pure gaming bliss. If you show me an engie point on either badwater or goldrush, between demo, soldier and spy, I will know exactly how to dismantle that mammajamma, and if none of those work I'm happy to roll medic.
Oh man, that reminds me of how I practiced some gosh dang ridiculous demo jumps back before they limited the sticky jumper to 2 bombs - just pure momentum riding the sides of maps.
I should try to play more, but it's hard with that community server magic gone.