Lazytown.
My absolute favorite map on TF2. I am pretty sure that 70% of my hours spent on TF2 is on that specific map. Unfourtunely the clan that I played on that had that map on 24/7 had to close down a few months ago and I haven't been able to find another busy server for that map with a good ping for my location. :c
Personally, I like to call Mountainlab my home. I'm just curious to see what you guys think.