It may not be the best looking, but the flamethrower in TF2 is the most fun to use. You can actually kill something with it. Unlike Nazi Zombies in CoD:WaW where it feels like you'd be better off farting at them.
I haven't played GoW2, I suck at handling gory games.
I might try TF2 then!
UT2004's BWmod would be my favorite flamethrower, but it's a mod. It lets you right click and spray fuel on the ground, etc, then just tap left click and anything soaked in fuel ( including players or yourself ) is set on fire.
Also, shooting the tank on someone's back makes it start leaking, it eventually acts like a jetpack and sends them high into the air before exploding.
I have the orange box, I just never really played it because I have an issue with aiming in source engine games. UT I can just headshot all night long all the way up to "Ultra kill!" with aim assistance off against the inhuman AI, I get into source engine and I have trouble aiming even with the rocket launcher in HL2.
Not really a flame thrower, but I just loved shooting bots in the chest with the flare gun in the original Blood game, they would run around screaming for a few seconds then burst into flames LOL. I am trying to remember the first game I played that had a flame thrower, I am not sure but I think it was wolf3d , whichever it was it was awesome and all others since have not been as fun/effective.
the one in aliens vs. predator because, if lots of aliens running towards someone, whip out the flamethrower for violent cooked aliens, as soon as flame hit them they were done for, a space marine has to defend himself, apart from that, longer range on the flamethrower and longer lasting ammo for the flamethrowers good