I think parallel is fine. I enjoy ATG, but I think the emphasis on ATG is a little overblown. ATG forces max effort, of course, especially by the quads at the start of the contraction, by hams and glutes for the rest of it.
But very few of us ONLY do squats, in which case you'll have another shot to hit your quads more directly, with more precise intensity. Leg extensions, presses, smith squats - whatever else you do, you can get your quads a little more.
Also, remember that going ATG can easily cause knee-related complaints in lifters who aren't already experienced and flexible. It's great if you can do it pain-free, but it's just a rough bet to make. If you hae no pain now, that's great, but I know a number of guys who had no knee issues UNTIL they started doing ATG on squats. And this was on varying foot placements.
I go to parallel now, and I find I can control my proximity to failure much better than with ATG. Squats rule for absolute leg size, but I think you have to consider your whole routine as the size-generator, not a single portion of one lift. Squats for overall thickness, extensions and presses for quads.