Take a look at the sticky in the New Divers subforum, about how to choose a dive instructor. What you care about is the class, not the agency. You want an instructor who has some experience, but hasn't been teaching so long that he's burned out and no longer cares. You want a schedule that permits adequate practice time, preferably spread out over several weeks, so that your subconscious has some opportunity to integrate things, and you have time to ask questions and repeat things that aren't really smooth yet.
I have seen PADI classes that are done well, and classes from other agencies that were not. The only agencies I know that really mandate what I would consider a proper length of time and amount of practice are small, boutique agencies whose classes are not widely available, and they also tend to be quite expensive.