I own CMC, Elftmann, Rise Armament, and Triggertech triggers in AR platforms. I have been happy with them all, but I will keep buying Elftmann. The Elftmann 3 gun is my go-to trigger until something as good and cheaper comes along. Rise Armament makes agood, solid, truly drop in trigger for under $100, but I like the crisp reset of the Elftmann closely followed by the TriggerTech.He will use it for plinking, informal target shooting and home defense. He insist it must be 100% drop in. I think that means he wants it to be adjusted from the factory and he will not be required to adjust it.
Realistically, ANY trigger is better than factory for most AR's under $1500. I have also converted all but one of my AR's to a straight trigger - for me it is more user-friendly and predictable.