Most modifications are simply a waste of money and reduce reliability.
Optics improve the situation, but little else does.
Standardized rifle setup are best. You’re probably going to lose that rifle at some point and none of those mods make you a better shooter.
The AR trigger is perfect under combat. Fancy benchrest type triggers are just a waste of money and often break.
The standard “birdcage’ AR flash hider is best. It works at hiding the flash and keeps the muzzle blast from being redirected down when in the prone position. It also helps as a muzzle recoil device. Trying every fancy thing out there is just a waste of money.
One item I do use is the tactical latch release. It allows quick charging handle operation with the typical two-finger salute.
Lights are good in some situations. A green laser is another.
I've stuck a Larue trigger in all my AR's, with the exception of my BCM. At $80, it felt even better than my Daniel Defense stock trigger. But you are right, some of those competition triggers are exactly that....competition triggers.
Best mod for a standard AR 15 is to shim the barrel and the pins on the upper/lower. Very little cost and relatively simple to do with the right tools, but will make even a cheap Delton kit into a tack driver. We have done several and every one resulted in very significant improvement in accuracy. Add good optics and good to go.