Honestly, I don't at all like how bots like G2 Op and Armada Megs look with the moving shoulder pylons. They make me not want to use what articulation they have because they look so much better with their arms straight down. The new molds might have some limitations on their artculation, but they still have plenty enough for my needs, and I much prefer the way they look while using it.
In an ideal world, I suppose I'd prefer both - arms that can move independently of the shoulders, and also shoulders that can rotate to allow additional articulation. But barring that, I prefer the Legacy implementation over the originals.