I am sorry I strongly disagree with these overpriced programs. They will not prepare you for an airline assessment for various reasons:
1. You don't know what type you will be checked on. (A320, 737, Embraer or other)
2. The date you do such a course can be months or even years before you get a real chance, unless practiced regularly it will give you little help by the time you finally have an assessment.
3. As a Cadet they will not be assessing you for failures etc. If you are non type rated they will check your general flying / handling skills. The HR interview will in 90% of the cases by equally as important as the sim.
4. MCC is the regulatory requirement, get the one that is "cheapest" possible, save your money until you know you have an interview / assessment. Then book Sim with instructor, same type as assessment. Most sim profiles for assessment for companies like RyR, Wizz, Ezy, BA and more, are available, and you book one or more Sim sessions shortly before your assessment date, and practice exactly what you will be expected to perform in your assessment.
5. No airline will give if you have some Certificate from either of these places, equally from places like Oxford etc., you doing a MCC course spending a few thousands, while they have integrated cadets spending over 100.000 Euros, will not count for the same from the FTO if they do have a connection with airlines.
EASA requires you have a MCC only, some airlines asks for a JOC, again if you do have to do it, do it as cheap as possible, as this has very little value when applying for a job, besides that you have to have it on your CV.
Rather spend 1000 - 1500 Euro on a Sim when you have an assessment, save your money until then.