What makes the RMR better than the other options on the market?
Three words,,,, Quality,,,, Durability,,, Flexibility.
I do/have owned many different types of Trijicon products. I currently own an ACOG, Accupoint, Pistol Iron NS, and now a couple of Reflex optics. IMO,,, you get what you pay for when it comes to anything Trijicon.
I currently have two Burris Fast Fire II's, an Insight MRDS, and two RM04's. The Burris is great for plinking,,, but it WILL NOT hold up to every day use,,, or any rough handling what so ever. The Insight is built well enough to take the every day use stuff,,, but it's poly housing won't take abuse. (accidental or intentional), and you have to watch yourself with it when using gun cleaning solvents etc.
EVERYTHING about the RMR is better than the other items I have listed. The controls are more rugged and more exact in the way they function,,, they work as intended, hold zero under crazy abuse,,, you can choose between dual illum models or battery powered LED models with the RMR. Most other manufacturers do it one way,,, and you live with how they think it should be done.
AND,,, if you pic up a used RMR for a decent price,,, you can flip it tomorrow and get most of your $$ back. You just can't do that with most models,,, because not many (none that I know of) will hold up under the conditions the RMR will put up with.
Do a quick google search for RMR durability and see the kind of stuff they take with people "trying" to brake them,,, now realize you won't put it through anything like that, and you will understand that it's money well spent.
Here's an analogy,,,, Burris = Taurus. RMR = Sig. Nothing "wrong" with either, and they both "do" the same thing,,, but they aren't equal to one another in any other way.