Manual is not for everyone though. I never play manual in previous iterations.
Personally, I prefer PA1 to manual passing. (I am talking about PES here, as it is my experience).
I believe that stats matter more in PA1. They matter a bit in manual (it's not 100% manual as has been said) too, but honestly I prefer more stats weight. I want to feel more like I'm playing with the actual players' skills, but it's a matter of personal preference. I will sometimes experiment with manual too, but for campaigns usually PA1.
That being said, I do enjoy a more "semi" or "intermediate" passing assistance, like in FIFA, or PES 13 or 14 one-bar passing, that's fun too. In fact, semi passing would be my preferred option if it were available in all PES.
Saying that there's a right or wrong way to play PES is something I disagree with. Play however you want. There's no one more valid way than another if you are playing in offline modes, anyway. I have felt much more pass difference between say, a Kroos pass and a second division midfielder in PA1, especially in through balls, and I find more enjoyment in this mode.
The most important thing is whatever is more fun for you, whether it's PA3, PA1, or FUMA. My two cents.