THERE IS NO SUCH THING AS BEST!
In anything. There are only a set of compromises that fits your "mission".
What do you want to do with it?
Do you want to sit at a bench on a 100 yard range and shoot tiny little groups?
Do you want to roll around in the mud and do training classes?
Do you want to bump fire all day long?
Are you planning on shooting p-dogs?
Using it for coyotes?
While ANY AR-15 is capable of doing all of these things, some are better suited to it than others.
Buying the rifle and optic/sights/ammo that will suit your uses will be better for you in the long run.
To quote a famous trainer: "The mission drives the gear train."
If you don't know what your use is going to be and you just want an AR, my advice is get one with the best resale value. This means something with name recognition with the largest segment of the gun buying population that is in as close to "military" configuration as possible. That way if you get it and it doesn't suit your uses, it can be sold to fund what you really need.
That means Colt, S&W, Bushmaster, or DPMS. Look at your local gun shops/gun magazines and see what brands are moving and prominently advertised. Buy that. Try it out, see if you even like it or not. You might not.
There are lots of other makers out there that make extremely high quality rifles but don't have the name recognition that will help you sell it if you get it and find out it isn't what you really wanted.
Based on your "requirement" for a 2 stage trigger, I am assuming that you want a benchrest type rifle? If so, you need to determine what range you are going to shoot at which will determine the weight bullets you will most likely be using which will tell you what twist barrel you need to get.
As an aside, if you are like "most" AR buyers and are planning on blasting away with surplus 55gr and 62gr ammo at 100 yards or less you are wasting your money on a 2 stage trigger. Your ammo will be the limiting factor in accuracy, not the weight of your trigger.
As an aside in my personal experience with my own and family/friends ARs.
5 Colts - 0 Problems
7 Bushmasters - 4 issues including 2 that had to go back to the factory
1 DPMS - Bolt would not unlock, had to replace bolt.
2 S&W - 0 Problems
Of course, YMMV.