Better is a relative term , lots of guys will claim how great Colt is ( mil spec bla bla bla ) but at the end of the day , my RRA Varmint, Noveske Barreled custom, WOA custom and LMT all outshoot my Colt . Not really a fair comparison because despite the "quality" all the Colt guys talk about they really dont use anything special for barrels
What do you want to use the rifle for?
Don't forget, although we can talk about quality / mil spec/ proper staking of carriers , taper FS pins etc, for most of us cilvilans this is a moot point - all our ARs in Canada are range queens. All the brands you mentioned are good brands . Since we are stuck using them at the range, accuracy to me is important.
If you want a very accurate factory rifle out of the box RRA Varmint will do .75 MOA at worse !
As someone already mentioned the triggers on the colts are nothing to write home about ( again, Colt doesn't claim to have match triggers ) Both RRA and LMTs 2 stage triggers are well worth the premium $$ of their standard
What is your budget ?
You will end up with a FAR better rifle ( and learn lots in the process ) by building a custom with good components . Don't scrimp on the barrel . Buy a Noveske ( Pac Nor ) / WOA / Shilen etc . That will be the hardest component to source here in Canada ( unless you will be satisfied with a plain "mil spec" barrel ). Only problem is its easy getting the black rifle disease and before you know it you have sunk stupid amounts of money on the latest rails, optics, carriers .
Other than a LMT MRP, I haven't bought a compete upper in years. Much more fun going custom. Its really not hard to put one together. There are lots of drop in trigger modules available ( Timminey / CMC etc ) that anyone can install properly.
If you have lots of $$ buy a finished custom like a Noveske / Les Baer / Wilson Combat .
Only downside is you will spend far more than what a Colt is worth