The red dot (AIMPOINT) or holo (EOTECH) sights should be good out to 300 w/o problems. If you want precision work for mid/longer range engagements, the ACOG is the way to go.
I have several ACOGs and my first one was bought almost 8 years ago. It is the perfect patrol optic on a 20" upper. My next build will be an 18" SPR with the 5.5x ACOG.
With my 4x ACOG, I have successfully engaged head sized target at night, just short of 300 yards.
I can engage targets out to 600 yards with confidence, day in and day out.
I have used it successfully covered in mud, freezing my ass off in snow, and dripping wet "near hypothermia" in freezing rain.
I can kick doors with the ACOG, although it is not my first choice optic for close quarters.
IMHO it is the ultimate do it all optic.