The new mini-14's actually have surprising accuracy. Ruger changed/refined their manufacturing process and even went as far to replace some of the machinery in the machining process they found to be causing the mini-14's accuracy issues.
The newest "target" models with the adjustable harmonic dampener can hit MOA or less, even up to 300yds. The catch is not everyone wants a big, bulbous tuner on the end of their rifle.
Just for supplement, here's a range report posted on YouTube:
A mini-14 target will run you about $850, about the same price as an entry-level AR. So, the question is, do you like the mini-14 over an AR? If so, get it. If you're just looking for something that shoots 5.56/.223, then go for an AR, as they're far more upgradeable.
And just FYI, the mini-14 CAN shoot 5.56. Some of the older barrels/manuals listed them chambered for .223, but they were in-fact chambered for 5.56.