Here's my suggestion when having a look for systems on Myfxbook:
Is the connected broker reliable? Is the broker well-known and regulated by good regulators (like FCA, BaFin, FinMa, IFSC, NFA, ASIC (only for Australian traders!), ICB, ...). Keep in mind: VFSC and FSA are not regulators for international brokers (it's just a company license not a regulator's license)!
Why? Because there might be some faked results being shown on the connected myfxbook system pages. Brokers come and go, they can be just created to show fake (to good to be true) results to possible clients and to scam them with faked EAs or PAMMs at the end.
Another good question could be: Is the system working with other (good) brokers aswell? or: Can the system really work with my already used broker?
The max. account drawdown needs to be lower than 20%. If it's higher than 20% the system creator should definitely can explain it, like with a short spike, a testing period at the beginning (with a small deposit) or something like that. Also have a look on the DD charts by yourself, not only on the number on the left side of the system (click on custom analysis and check the 'open time' box in 'timing' for a better analysis).
Have a look on the history, to get to know if the system creator is using only low risk (low lot sizes and not much trades per day if no SL/TP is being used, or a good/low SL if higher lot-sizes are being used).
That's it. All the other numbers are not really interesting, just showing you how your results could be if you'd use the exact same system/deposit/trades/broker etc.