Trading conventions

In which difficulty do most people trade?

For example I'm trying to trade a bartucs and a Ko rune for pgs, where should I make a game?

I pressume nightmare is the best choice, or are there any trading conventions? Like people lurking normal games with mules etc?

Thanks in advance! :)|||Usually it's hell, however you might see more pgm related trades on normal (people unloading mules). Nightmare is useless for trading.|||Thanks alot nurman :)

I usually made my game in nightmare because I figured it was the more neutral choice ;D