Mine is the spy, though I don't play him as much as the demoman or engineer. He's my favourite because he is the coolest =D

eh, I prefer spy as well, though I do play soldier ( though that is mainly for scrims).

EDIT - Thought I was in General Discussion. I have to go with the Sniper.

Sniper

Heavy Weapons Guy, but only when I have a good Medic
Either that or Medic, but only when I have a good Heavy Weapons Guy
And when I have neither of those I go Engineer

My favorite is definitely the soldier. There's nothing like a good rocket gib or taking down a bunch of sentries with an uber.

I do like the spy, just because it's fun, but I believe I like the Heavy or the Pyro the most.

Solider or spy

Medic I think - it can be quite a challenge and planning tactics carefully with a friend playing a high damage class is really effective.
Engineer is probably my second favourite - because of tactical placement of turrets etc.

I started off playing Spy, but gradually moved over to Pyro which I enjoy far better now.

Spy FTW!

Medic,  Love the uber rushes.

Pyro or Spy

Demoman but it seems like my favorite changes every couple of days, or depending on the map.

I despise Snipers, but it's still my best class.

My favorite class is probably Battle Engineer or Crab-Walking Spy.

*looks at pic* You get the idea

thank the lord there are no battle-medics here.

i like demo. and scout. :) but more demo o.o

"i like demo. and scout. :) but more demo o.o
"

Spy i think

Spy, I always play him

I love the sniper. I'm terrible at the class, but I find headhsots so satisfying.

Spy is terrible and you should all feel bad for liking him.

I have the most time played as a solider, but recently I've been playing an engi more and it's a lot of fun.

Heavy, Spy and sniper.

Pyro, Demoman and Heavy.

"Spy is terrible and you should all feel bad for liking him.
"

Pyro, nothing like air guitaring over a burned enemy.

Pyro is my favorite, gotta love that flamethrower. 

"Demilich said:

"Spy is terrible and you should all feel bad for liking him.
"

give me the reasons
"

Pyro

Pyro

pyro and spy are my favorites

Pyro for sure, no other class can be as awesome as he is.

Spy is a lot of fun. I've also really been enjoying Pyro lately.

Heavy is fun too.

I play as medic most, but I enjoy playing the spy the most. Its just a fun class.

"dartagnan said:

"Demilich said:

"Spy is terrible and you should all feel bad for liking him.
"

give me the reasons
"

They ruin my Heavy runs ><
"

Spy. The most skill. The most satisfaction.

It's probably the hardest class to master, or even be decent at. I've seen so many terrible spies in my day it's rediculous.

But I do enjoy the occasional Scout rush on 2fort.

"Demilich said:

"Spy is terrible and you should all feel bad for liking him.
"

give me the reasons
"

My favorite is the engineer. Turrets rock my world.

I try to fill in any missing aspect that the teams needs (no heals? Medic. wheres the defense? Engi etc). If not, Spy.

Good question, Hard choice. I guess my favorite class is either the Pyro or the Spy.

The Medic is my favorite by far, mainly because I have a hard time keeping up with aiming.

mine is the pyro, i just started playing with him and I cant stop :(

Sniper.

Nothing more satisfying that taking out 4 enemy snipers who are all trying to get you at once...

Scout is my favourite, however if needed I'll go Heavy.

Pyro is definitely the bad-assiest for me

The demoman, I play as that class all the type for I am the best demoman evar!

I like the Medic or Heavy.

pyro, medic, scout, then soldier. I would like demoman, just im dead aweful with him