Colt Canada (Diemaco) is basically a boutique gun company making finely crafted firearms in limited runs for some of the most discerning customers in the world. Is it the fact that the US Navy Seals or Delta Force doesn't use them make them a bad rifle? No it doesn't, they have a lot of domestic and international suppliers of rifles to choose from, and I for one have no clue if any Colt Canada rifle could even be put forth for consideration as Colt US is the domestic supplier for the US Army. And remember, Colt Canada's rifles are based on the complete Military specifications supplied to Colt US and purchased by Colt Canada, with Colt Canada, reviewing and improving on over 200 aspects of this rifle.
I could have bought a Daniels Defence, HK or Sig Sauer, but for the money, the build quality and that it's CANADIAN, I bought a Diemaco SA20. I do think it's among the best in the world. If I want just a Canadian made rifle I could have spent far, far less and bought something else. I've tested other rifles and not one rifle felt as good in my hands as the SA20. I've traveled all over Southern Ontario to shoot different AR's including Daniels Defence, and when you're shooting, seeing the ignition of the gun powder in the chamber through the crack between the upper and lower I get jittery.
My Colt Canada SA20 is so precisely made that the tolerance and innovations that go into that CANADIAN made rifle mean I don't see a flash in my left eye as a bullet goes down range. And that sold me on this rifle.
Now are there "better" rifles? Depends on what you're measuring and how much money you're gonna plunk down on the counter if you can even get them in Canada. For $1,800 Canadian out the door, I think I got the best dam rifle in the world. But that's my opinion. If you can and want to spend $3k, $4k or $5k on an AR15 rifle, then more power to you and your choices may be far more exotic that a humble rifle made in Kitchener, Ontario.
If Colt Canada didn't offer the SA20 for sale to the civilian market, I would have might have gone with an HK or Daniels Defence as I believe Sig Sauer only make Piston Driven AR's.