this seems to be a common ques. there are so many good ones out there, that i have a hard time any knocking of them. however, everyone thinks colt is the cadillac of ar-15/m-16's and it truly isn't these days ( plus not all parts are interchangeable0! i own a pre 1970 and love it, it was my first in a long love for the rifle. i am currently building a rock river arms ar-15 because of all of the advice i have followed. it's not a cadi, but it is a great lincoln! lol the bad news is, that everyone is doing what we are right now, so everything for an ar is at a premium. remember, most lower receivers are the same, and you probably won't go wrong with too many of them..