I can provide some generalizations.
The 1:9 twist likes 55-75gr ammo, but is generally the most accurate with 62gr + ammo. For range purposes, I like to use decent quality American factory made 55 or 62gr FMJ. I've found it relatively inexpensive in case lots from Winchester (223 and 5.56, including the Israeli-made Q3131A), Remington,Federal, and, a personal favorite, Black Hills. I get good reliability from all of it, and if I don't, I have a box with a batch number, manufacturer, date of production, etc.. which I can use as a reference when talking to the ammo company should I need to. Straight from the box/case, I also have an assurance that what I got is what I thought I was getting, rather than an advertiser's word for it that the ammo is "top notch, recent manufacture, non-corrosive,foreign military order overruns".
Defensive applications are somewhat different as they depend on engagement range, target background, penetration, and othr factors. Again, good quality FACTORY ammo that you've already tested in your rifle is going to be your best bet, both from liability and reliability standpoints.