Which difficulty do you find more rewarding to complete a game on?

Whichever one is challenging and not frustrating

Obviously, the harder something is the more rewarding it will be. But with greater rewards comes more frustration; a lot of the satisfaction comes from overcoming the obstacle of extreme difficulty.

Usually hard is a good place to be. If it feels cheap and just a shitty way to make a game longer without any new content, I'll just switch to normal. 

I usually start on the easier and and build up the difficulty with each subsequent play through of any game. Sometimes if I am very familiar with a series' game play I might go straight for a middle or harder setting  but that isn't too often. I find the higher I climb the difficulty the more rewarding it is though.

I just play on normal. There are very few games that fuck up normal difficulty.

Beating cod4 on veteran was the highlight of my video game career. 

Most of the time I will play on the difficulty just above normal. If it's a game where I have little experience (like Starcraft 2, since it's an RTS) I will go for normal. Then if I really liked the game, I will most likely play through it again on the hardest difficulty, if only for the achievements. The most rewarding is the difficulty that challenges you without frustrating you, which is usually the hard difficulty.

I always play normal first. since it is called normal as well as the default setting for many games, I am presuming it also has recieved the most attention with regards to balancing. I don´t remember ever (at least the last 10 years) setting a difficulty down due to toughness. When I feel like I want to do that it is usually due to frustrations with design, controls or me just not being in the mood for that game, so I tend to throw away the game at that point instead. 
 
When I´ve completed a game on normal, I usually choose the harder for a second playthrough (though second playthroughs for me are rare. Too many great games yet to play)

The one that's challenging, but not too frustrating. It varies from game to game -- sometimes it's Normal, sometimes it's Hard, and sometimes it's Very Hard.

I wish more action games would use the dynamic difficulty system introduced by God Hand. If they did, that annoying scenario where you choose a difficulty setting only to find that it's way out of your league -- or so easy as to be boring -- would cease to exist.

Depend on the game. Usually when a game is well designed and adjusted on both normal and hard difficulties, I'd feel great beating them both. When normal difficulty bored me with repetitive enemies placement and bad pacing, I'd probably enjoy hard. It really depend how the game is designed.

The worst is when a game has only 1 difficulty mode and badly adjusted, fuck that shit, and another is they put in hard difficulty but did nothing but just give them more health and higher damage, or mindlessly add in more enemies on screen, fuck that shit too, you could usually tell when a developer is being lazy about it too.

Normal. However as a kid it was easy.

Normal first then it's always a challenge for me beating it on Hardcore/Impossible especially on COD: World at War man that was a discouraging experience having to stand behind a rock picking off one guy every five minutes and who can forgot those goddamn grenades some would say the achievements are worth it in the end all the others who do it for the self-confidence well there just plain masochists attempting to lose there sanity.

Normal, or one level above "easy" if it exists.

I prefer hard over like insane mode settings. You can still progress at a reasonable rate, but still take some chances.

i just start the game on the hardest setting, single player games are easy once you figure out the right technique per level/mission/quest ect...

I used to play games on one of the harder difficulty settings but then work and real life got in the way. I only play FPS shooters and simulations at hard/realistic nowadays and play everything else on easy so I can get through the bloody game within a couple of weeks instead of months. Somehow the stories being told, rather than the difficulty, means more to me.

In FPS's I generally go with default because in most games, increasing the difficulty means slowing down the shooting parts.
 
In RPGs or RTSs, I usually go with hard setting.

I usually roll on normal the first time through, but it really depends on the game/genre. I'm playing through SC2 on Normal right now and it's really underwhelming.

this really depends on the game. I like to play shooters on hard if not impossible just cause I actually sort of like the die 5 times per checkpoint, figure out how to deal with each scripted situation thing. On the other hand If I'm playing civ 4 I have no chance unless I put it on prince or lower, although sometimes I'll try a harder setting just to see how fast I can die. I do wish however that games would stop trending towards holding your hand through things, if ever a shooter comes out where you can't die we've lost the fight.

I feel  rewarded enough by finishing a lot of games on Normal but  if I do try out hard or insane modes I usually feel a whole lot prouder of my achievement., especially if the game in question is insanely tough. It also depends on my love of a certain series or game before I try out harder modes. I must admit that achievements have played a large part in me wanting to try those modes in games i otherwise would have just played on easy or normal.

" Whichever one is challenging and not frustrating "

I tend to play games on normal at first, but the higher the difficulty the more rewarding it is. 

" I just play on normal. There are very few games that fuck up normal difficulty. "

Normal or one above :)

The one in which I loose/die couple of times in a mission/level, but is not impossible for me.
Usually takes me a couple tries to know which one to go for.

For me, the difficulty before the highest is usually the most fun to play. Any lower and I'm probably playing just for the story. Any higher, and I hate myself.

C most of the time.
 
But there's certain games I like to co op on advanced/legendary/fuck me this is hard modes.

Hard. It usually pushes the systems of the game without making it ridiculous. And you usually don't get a trophy for insane.

Depends on the game. If it is a game where I want just experience the story, I will play it on normal first. Then I usually go back and play it on the hardest difficulty.

Normal. I knock it up to the hardest difficulty if I really like the game and want a challenge, or if I feel like whoring some achievements.

For me, the most rewarding difficulty to play a game on is the one that gives me the chance to have as much fun while playing as possible. It's simple, really.

EUROPEAN EXTREM - since I am european!