The highest is called NOIR and is by invitation only. There are a total of 5 tiers in the M Life system. That having been said, it's much easier to climb the tiers in the Caesars Rewards system.
The high-end of MGM properties include Aria and Bellagio which both get a grade of A from me, while the best Caesars property is probably Caesars Palace.? Caesars Palace is at best B+ in my book.
In terms of quality of property, MGM Resorts (M Life) is much better than Caesars Entertainment (Caesars Rewards).
