I am looking to get my 1st and only AR-15 style weapon. My prime concern is reliability. I have heard the negative comments on the AR-15 in this regard, but am hoping to head off any problems by proper weapon choice. I was hoping to keep the barrel length 16 to 18 inches and get a flattop with BUIS with the goal of some kind of optics eventually. Alternatively I would consider a dissipator type setup (longer sight radius means better shots for me) with a removable carry handle. Bottom line is I value most the reliability, then portability (ie. low weight and size) then accuracy of the rifle.  Any suggestions?

The ABCDR's are your top-tier manufacturers. Thats A=Armalite, B=Bushmaster, C=Colt, D=DPMS, R=Rock River Arms. They all produce very reliable rifles. However, you must do your part too. You need to clean your rifle after you use as well as use quality USGI magazines.

I am looking to get my 1st and only AR-15 style weapon.

ONLY!?!I don't think that's possible once BRD sets in.

Kolt(+400 for the name)
Bushmaster
RRA
These seam to be the top picks.
Can't comment on the rest of it.