I think a better question might be does 6max or 10full have more bad players? I know for low limit holdem, 6max definitely has an overwhelming number of bad players and would theoretically be more profitable in that sense, assuming you could play shorthand well. But I haven't played 6max for no-limit yet. I think 6max, in the same way as Omaha and pot-limit games, naturally attract worse players who like to gamble a lot.