Symmetrical, probably mainly because I play on Dualshocks for 15 years and simply got used to them. But I think it has something to do with ergonomics, like you know, my hands are quite symmetrical, so laying down my thumbs on symmetrical sticks feels natural.
Didn't try it, and probably never will, but right now looks like Wii U Pro Controller does it very good, great shape and sticks on top, I wonder how it plays.
But judging by the feedback, Dualshock 4 nailed it, repaired the flaws of DS3, keeping a similar scheme and still quite keeping the Dualshock identity which is a undoubted symbol of the PlayStation, can't wait to try it.
So it is happening...PS4 preorder.
Greatness Awaits!