0-300. How light/heavy do you want it to be? How accurate at those ranges?
1-4x 30mm scopes are ideal for these ranges if you need to be accurate, or fast. But they weigh a pound or more.
Aimpoint are great for simplicity and durability. A 1x red dot with a 4 year battery life. Primary arms makes some very decent knock offs for very reasonable prices.
Holographic sights like Eotech are not my favorite by far, but supposedly have super quick target acquisition and some people love them.
Reflex sights like the Burris fastfire are super light, not quite as durable as the others but work well.
A good 3-9x is great for varmint and target work inside 300.
My first optic on an AR was a fixed 6x on a carry handle. Terribly difficult to use, cheek weld way too low, scope distance over bore made bullet rise/drop a lot more dramatic.
If you can use irons, nothing wrong with them. I keep a couple optic free because I'm not made of money.