When you say "a Ryanair approved school" I assume you mean CAE in Amsterdam or SAS Flight Academy. Either of these are an excellent choice for an MCC course if you are aiming towards a job at Ryanair - they use Ryanair's MCC course. The course itself is done on the 737-800 simulator and therefore gives you a good grounding on the aircraft for when it comes to the all important sim assessment. PARC is also good because they use a 737-200 for the course which gives you a chance to really fly a jet. Again, this will help with the sim assessment. Doing an MCC course on an A320 won't do much for your jet handling skills.
However, I think what you are really angling for is which is better for the all important inside line to the elusive Job. I would guess the approved schools are a slightly better option as they can put you forward for interview. Thus, if you have the ability to do the job, the motivation and the desire then go to one of the schools. Having said that, there is a large uptake from the PARC MCC course as well.