>>569459
First, what's your budget?
If it's high: Trijicon MRO and Browe Tactical optic (good ACOG clone that may be on sale for around $850) laso, check out the Primary Arms Platinum line of scopes.
If low: Sig Romeo 7 or DI Optical RV1. Both totally acceptable and rugged (Especially the RV1) and have similar function to the M68, which I have also trained with. Eotechs can be had on sale here as well.
For ranged use here, I would suggest the Primary Arms ACSS scopes. Great reticle, good price. Rob Ski has used them extensively and claims that while they're not as good as an ACOG, you would have to do some really dumb shit to break them.
Source: I have an MRO with MI mount on my AR and a PA 2.5x ACSS on my G3. Have trained with M4 and M68 CCO combo (limited).