My son, while in the 160th SOAR in Iraq/Afghanistan, frequently shot "practice rounds" with his "customers" - SEALS and DELTAs. They all used Trijicon ACOGs. Now, that was during the 2008–2010 time frame and scope technology has changed since then.
One thing my son preached was to decide why you want a sight, then select the optic that has the features which best suit your specific needs. Generalist sights will be good, but never the best. Don't be surprised if you need more than one style, depending on the circumstances: long-distance fixed-target shooting versus quick-target-acquisition-close-in moving targets, etc. Reticle shape, color and relative distance features are variables to consider. Cross hair sights, chevron sights, etc. are designed to fit specific circumstances. Red versus green reticles are, too. Fixed vs. variable magnification is another consideration. And fixed magnification opticals augmented with separate magnification opticals adds yet another variable. The choices are almost infinite.
Primary Arms makes a variety of good, low-cost, general-purpose sights, and their website has a great set of discussions that address the above issues. They carry their own brand as well as other makers' sights, and their prices are very competitive.