TF2 is a very versatile FPS. The gameplay, items, crafting system and various classes make it one of the few FPS that doesn't become mind-numbing over time.
So, what is your favourite class?
(http://files.g4tv.com/ImageDb3/143904_S/TF2-Sniper.jpg)
It was a tough choice for me, Engy or Sniper, I love them both. In the end, sniper had the upper hand. Hearing that "DING!" off the head shot, seeing over 500 damage, and looking at the pink mist. So satisfying ;D
Recently I have been going back and forth between the Machina and the default rifle. A good portion of my kills are from the Deus Ex Machina, however I was growing tired of the tracer. It [machina] is great for a majority of kills with the damage buff, you can literally shoot people in the leg and get a killing blow. I did however, and maybe this is in my head; start to feel like the weapon was heavier and less versatile than the default rifle. So now I go back and forth, depending on my position on the map. The sniper can be a versatile class.
Team Fortress 2 "Meet the Sniper" Trailer (HD) (http://www.youtube.com/watch?v=PyNuriXG3BQ#)