Having once owned, before the boating accident, both the Mini and the AR-15, I believe the new Mini to be a superior end-of-the-world rifle.
It NEVER, EVER fails to fire. Even without cleaning and after thousands of rounds.
The heavier barrel on the newer ones overcomes the accuracy problem of old.
The ONLY advantage of the AR is that everyone else has one and you can share magazines.
And there are a gajillion aftermarket parts for the AR platform and with an upper change, you can quickly change calibers.