I think that if your leaning towards a Daniel Defense, you have already made up your mind, and in my opinion you have made an excellent choice. I was in the exact same position as you are about 8 months ago, and decided to build my dream rifle. I too played with the idea of building vs. buying out of box and in the end i went with a Daniel Defense DDM4A1 in Mil Spec + and I seriously couldn't be happier. I have well over 1000 rounds through it, and it never stops. Buying out of the box will give you the piece of mind knowing your gun will work when you want it to. My friend had a very experienced gun smith build him a rifle, and it was having gassing issues for a long time. My opinion is buy a DD and be happy, end of story. Here is my rifle (I do like the Aimpoint, i think they are a phenomenal value and built like a tank).
My dream rifle was around the $3000 mark.
-Daniel Defense M4A1 Mil Spec +
-BCM Mod4 chargin handle
-Troy Industires Font/Rear BUIS
-Surefire M600U Scout
-Haley Strategic Thorntail mount
-Aimpoint Patrol Rifle Optic
-American Defense Manufacturing AD-68H