I've found LeMayMiami's posts personally interesting as my LE career started ~1995 and I recently fully retired in 2017.
Throughout my career, for shotguns, we used 1 oz. rifled slugs in 2.75" 12 gauge from Winchester or Remington; and 00 buck, "SuperX" Winchester, again 12 gauge 2.75".
My prior department recently switched to the low recoil Federal 12 gauge 2.75", but still 00 buck, now with the Flight Control Wad, and the low recoil 1 oz. slug. There was some talk on Winchester's observed/perceived quality not being as good causing the switching to Federal, but this may have been more in the handgun ammo (Winchester RA9B to Federal HST, both in 147 grain) and not as much in the long-gun ammo. During my time there, the shotgun changed from a 20" Mossberg 590A1, first with bead sight, then to ghost ring sights, finally to a 14" Mossberg 590A1 with ghost ring sights.
For the now-older Colt AR15 guns, the department also switched ammo brands to Federal, but with a .223 62 grain soft point. Every officer didn't just get a rifle. Each LEO had to personally make a request to get the training class and be issued a rifle. I'm estimating maybe 1/3 of the 500 LEOs requested and got the training to carry an issued AR15 (firearms generally must be issued, no personally-owned, optional BUGs excepted).
I was never involved with what ammo was to be issued/approved/tested. Now retired, I'm still used to 00 buck and slugs, but would consider these other buckshot choices if I had to but 00 buck in various brands, all 12 gauge 2.75", always seems readily available online. I've got a good feel at estimating distance out to ~20 yards where I'll be switching to slugs (even with 00 buck with "Flight Control" wads) as each of the 8 or 9 pellets should not be missing the threat.
In other words, so far, I'm staying with Federal LE133 or LE132, along with 1 oz. slugs as an alternate, unless I read something which really tells me I should switch buckshot loadings. I'm only talking anti-bad-guy loadings and I've no idea what to use for anything else and what all those bird shot and other-buck-shot loadings are good for; there are just so many.
(SIDENOTE: One thing I really like is how much easier it is to clean a 12 gauge pump after the range compared to a handgun, AR15, or even my Remington 11-87P semiauto 12 gauge. I clean my gun(s) after each range session, the AR15 types being the dirtiest, most involved.)