I train at a 141 school. You have to have so many progress checks along the way before you can advance. In theory this is good, but not in practice.
I have accumulated at least an extra 12 hours on my PPL just waiting for the chief flight instructor to do my prog checks.
We use king ground school. You could use that at a part 61 so that is not an added benefit. I mean you could use whatever ground school you wanted at a 61.
Personally, I think whether you go with a 61 or 141 really depends on the following:
1. Cost of aircraft you will train in wet
2. Cost of instructor.
3. How well they maintain their aircrafts.
4. Availability of aircrafts/instructors.
5. Quality of instructors.
6. Are they organized?
My opinion is ask the questions above when deciding on which school to go with, whether 61 or 141.