Sailor, have both and will give you my experience for what its worth. My dad bought an early series 181 pencil barrel mini 14 in 1979, so I've used that one for over 30 yrs. The old mini's are not that accurate, I've spent a lot of time over the last couple of years trying to find the mini's preferred ammo and try to improve accuracy. At 50 yrds, from the bench using a rest, my mini averages 2-3 inch 5 shot groups. Occassionally I would shoot a 1 1/2 inch group but not normally. The new heavier barrel mini's have a better reputation for accuracy, but about the same cost as an AR now.

I bought the Sport last summer to give ARs a try. Shooting from the bench with the AR, at 50 yrds I wasn't doing much better, 2 to 3 inch groups. I put a cheap 4 power scope on the Sport and was able to shoot 1 inch groups at 50 yrds so the gun was more accurate than I was able to do with the factory sights (the LMT type). At 100 yrds using the Sport with a scope from the bench, I'm able to keep most of my shots within a 4 inch square, but haven't shot 5 shot groups with it yet. As far as reliability I have never had a jam with the mini 14 while using factory magazines, and have shot more rounds than I can count. I did have a few failures to feed with the mini using cheap Eagle plastic mags, so if you go with the mini definitely buy the factory 20 rd mags. I haven't shot the Sport that much in comparison, but I have had 1 reload get stuck in the chamber and not fire or eject. Mags are definitely cheaper for the AR.

I believe ARs are more accurate, mini's main claim is to reliability, use to be cheaper 223 rifle but not anymore. I bought the Sport at Academy for $599, if you look around long enough I hope you can buy one for around that. Cope dist was carrying Sports for $599 but they don't have any listed now, could call and ask them. If you decide to go with a mini, CDNN sells the tactical version (16.5 inch barrel) online for around $589 the last I checked.