arfur's final sentence admirably sums up PPRuNe policy on this. Word of mouth will bring you the names of those conducting MCC training with a stellar reputation.
Not the company, not the sim. The human being in the cab with you.
If doubtful buy a tame professional pilot a pint, those with many, many sim sessions signed up over the years in the same, identical sim. Each experience is made utterly different by the person behind them. They value they gained from each sim detail is entirely dependent on that person alone.
Rob Lloyd