To respond to the OP question.
I used the older designed M16 A1 in Vietnam, other than a slight jam I got one time, not critical, the Weapon did exactly what it was suppose to do, over and over again... my buddy.
I came back stateside and never looked at another gun, didn't want reminders ! In fact, I did a lot of stupid things so maybe it was better I didn't get into guns.
Moved to SoCal, SIL & Daughter, wife and myself went gun shopping, my SIL, a Marine, bought an M16, Military Style, and we had fun shooting , I was hooked !
I bought an AR15 with a few extras, but it was a great rifle and we all got some good time together shooting.
I more recently purchased this one: No Scope
20" Barrel, and very accurate, I don't hunt but if I did this is the rifle I would use, it drives tacks up to 100 yards on steel sights and with a scope, well I am in the market buying a new scope, but I believe it would go 300 yard with a quarter pattern. (just guessing here)
So what this boils down too is, I purchased my AR-15 because I used on one in years past and it got me through two years in Nam... and it is a really good rifle. Not to mention I had to compete with the SIL !