"But if you want to be a good instructor along the way, ATP might not be the best, unless you stay at ATP"

Even though I recommend ATP for the CFI's vs a small FBO, I can't really disagree with the above post. Larger academies who pump out a lot of CFI's at least know how to get a guy through it. Does that make you ready to teach new folks while going from PPL to CFI in three months? I think not.