Under Part 141, you must receive and log 120 hours of training toward the Commercial certificate. Private and Instrument don't count. 55 hours must be dual and there are several other requirements to be met such as 10 T/O and LDGs at a towered airport at night, as well as the required XC trips. In order to be a Part 141 school, the school must have a plan called a Training Course Outline which states what the syllabus is and how it will be used at the school. So the school has a way they must teach you.

Under Part 61, you must have 250 hours total to take the checkride. If you've done no 141 Commercial training at this point, you could choose to go either direction. It would be about the same number of hours. I had friends who left our 141 program because they needed 30 hours to get to 250 instead of the 70 hours the program would have required. However in your case, you have no definite advantage either way, but you have an opportunity to make a decision about what helps you the most.