I've only seen a few Colts but I've never been all that impressed. My buddy has one and the finish is terrible.
My first AR is a Colt 6940 with monolithic upper. Great shooting and perfect engineering.
The "impressive" thing about Colt is, they actually own the AR-15 patent (purchased from Armalite), was the sole producer of AR-pattern rifles for the military, and is the only make many police departments will allow their officers to purchase for carry on duty.
All other AR-15s are "AR-style" or "AR-pattern" rifles, since only a Colt can technically be called a true AR-15.
True that others may have made improvements in their models. Those are good, too. But if you want to be impressed, be impressed in the fact that Colt made all M16s and through 2011 all M4s used in actual combat. The M16 started production by Colt in 1964. Colt had the exclusive M4 contract from 1993 to 2011.
The other makers used model numbers and names other than M4, and were called by many "M4gery" (M-forgery). Colt sued to protect their patent of the shorter barreled M4 name. Bushmaster won a court case to use the name M4, as it's now become a generic name for AR-15 pattern rifles, even those with 16" barrels for legal US sales to the public.
Part of owning a firearm for many is the history of its design and the military's adoption and use of it.