here is a thread i made about two i own and like very much.
like the poster above, i have the M&P sport and like it very much (so far, i haven't owned it very long). i also own a stainless mini 14 and i think its a great rifle as well. imo, you would really enjoy either. both were a bit under $700.
although i know you stated .223, i would highly recommend a ruger 10/22 ($200ish), especially if you're budget minded! the kel-tec sub2000($300ish) always looked interesting to me, but i have never shot one.
here's my mini and AR.