For run-and-gun AR competitions:
Vortex Viper PST 1-4
US Optics 1-6
NF NXS 1-8

Long range AR and Bolt gun comps in ascending order of pain:
Burris XTR II 5-25
Steiner T5Xi 3-15
Steiner T5Xi 5-25
NF ATACR 5-25
Schmidt 5-25

The top tier stuff is all good, of course. My personal favorite for value is the Steiner T5's. I have three of them, and if you shop a little bit you can find the 5-25's (for example) lightly used for $1,000. Steiner's warranty and service is excellent, so I buy used without a care in the world. They run my favorite reticle, and the tracking is rock solid now that they've worked through their issues.

I looked through the new Burris XTR III last weekend at a match. They are killer for $1,800.