I like lightweight barrels and simple rifles.
This is one of may favorite rifles:
![Image](http://idfcarbine.files.wordpress.com/2013/06/basic-idf-carbine-clone.jpg)
That one has a Daniel Defense hammer-forged chrome-lined 1/7 lightweight 14.5" barrel.
My wife has a blue rifle built on a Cav Arms lower with the same barrel.
My 6-year-old daughter has a pink rifle built on a Cav Arms lower with a 16" lightweight Del-Ton barrel, but I think I am going to switch it out for one of the 14.5" DD barrels, since I have a bunch and no one is buying AR stuff right now.
My 9-year-old son just got one of the same barrels for Christmas to complete his AR. (My 10-year-old got a heavier match barrel, as he wants to build an SPR-type rifle, and I also have nice WOA match barrels sitting around - might as well put some to use.)
I will have to post photos sometime.
One thing I notice is that all of the gear geeks get misty-eyed over all the cool gadgets sticking to their rifles like giant barnacles on a whale, but any time they pick up a simple configuration like yours, they are always surprised by how much they like it. People with $2,000 in their ARs will pick up a basic carbine and say, "You know, I need to build one like this."
The Ergo grips don't work well for me (hurt the wrist when I am carrying the rifle for several hours or really running it) and I don't care for the add-on buttpads, though I do like rubber buttpads on my rifles. I run these buttstocks:
http://www.7-62precision.com/m4-ar-15-s ... r-buttpad/
http://www.7-62precision.com/recoil-red ... -15-stock/
http://www.7-62precision.com/m4-ar-15-s ... e-carrier/
One of the reasons is for the rubber buttpads. The way I run a rifle for counter-terror/self-defense use, I get a bruise on my chest even with the rubber pad. Without, I beat myself up pretty good, being a skinny guy.
I like standard front sight towers. They are tough, don't have to be flipped up, and whatever anyone says, they don't get in the way of optics.
If you get an optic, think about going with a full-sized optic. The optimum size for a reflex aperture is around 30mm or so for a fighting carbine. Once you put a riser under the smaller sight, it is really no shorter than a full-sized reflex sight. The micro-sized optics reduce some of the advantages that you get from a red-dot sight.
You can get lowers for less that are totally out of spec, too, so $115 is not too much to pay for one that is right and has a logo you like.
Midlength is nice. It keeps the 16" barrel from looking too long, and keeps the pressures down in the action.