As you well know, i'm a big fan of the straight "3d6 in order" method of character generation. However, I've also been involved in games where the "4d6 drop the lowest" and "2d6+6" methods were employed.
I was sitting here thinking about the distribution of ability scores that are generated using those three methods and thought, why don't I publish a chart to graphically illustrate the differences?
Here are the fruits of my labours. As you can see, the 2d6+6 method generates the most attractive sets of ability scores (from the players' perspectives), as they can never generate a score of less than 8, and have the greatest chance of generating an 18.