I think the .30 Carbine would supprise you, but they are getting expensive to buy. I like the AK47 and SKS. If you're going to upgrade the gun I wouldn't recommend the SKS unless you read all the 922r regulations before you change anything on the gun including removing the bayonet.
The AK47 is a proven battle rifle. It's cheap to shoot and reliable as gravity.
I bought my first SKS back in the 90's for $89 at Vance's and now it's hard to find one for under $300. An AK can be had for just under $400.
Ruger Mini's are good guns, but I've always thought they was a little over priced.
My vote would be for the AK47