Might be the best entry level red dot - Holosun Paralow HS403B 1x20mm 2 MOA Red Dot Sight

Features, price, and reliability wise, the 403b is that minimum for a "do everything" red dot. I dropped it twice and it went a bit out of zero. Both times were hard drops, on the rifle, from about 3 feet. Not a scratch. Impressed with the durability.