apples and oranges
To me, the AR and Mini overlap in some areas, but not all.
Its like stock car vs a F1 car. Both do a lot of the same things, but you can't put one down because it stinks in one area over the other. For example, you cant have a passion for 1" groupings at 200yrds and say the mini stinks.
Just as you cant say you love cleaning your guns with pond scum, and say the AR-15 sucks.
There are some things one rifle is going to do better over the other.
I love the how you can customize the snot out of an AR. Target, sprayer, different cals...you name it, you can make it work, and work well with an AR-15.
The mini does most things well, but its history, and "old style", etc.... make it an easy target for criticism.
I love my mini (560 series) as I found it to be OVERALL: 1.) easy to shoot, 2.) is not finicky about what I feed it, 3.) easy to clean, 4) "low profile" appearance,5) good general purpose weapon.6.) you can buy one without having to decide on 50 different options...but it does not perform well in all areas, and neither does the AR-15.
That's my $0.02...not that it's worth a lot.