3d6 in order a few times, IIRC, then 4d6 best 3 in any order for most of my gaming time.
I now use 2d6 plus 4. You establish an order for the bility scores (usually Str, Dex, Con, Int, Wis, Chr) You roll 2d6 6 times. You add 4 to each 2d6 result. That gives you a range from 6 to 16 for each roll. If you take them in order and apply them straight down the ability score list, I give you a minor side benefit (a mini-feat). If you want to move them around, you can, but no side benefit. This is the most recent revision of this plan. You can also opt to use 27 point buy.