I've got a S&W MP15T very reliable never had feed or ejection issues. S&Ws can be rather expensive but I have also heard DPMS makes decent ARs for a good price.
https://www.aimsurplus.com/product.aspx?item=F1DPMSRFA30C&name=DPMS+ORACLE+.223%2f5.56+AR+Rifle&groupid=8357
I know it is listed as...