Top of my head, worst uniques is a fight between the US and Portugal
What? Portugal's Uniques are way better. At least they do something additional in a timeframe you might actually get some novel use of them.
SEALs are actually dope for late game amphibious invasions, they are just, y'know, Marines -- a unit that comes very late, cannot be upgraded to and has to be built fresh (I always laugh when the AIs get Industrialization for this reason if my Tanks are already rolling, they have to take up build queues to make Tanks or Marines, no BS mass free upgrading Infantry for them!) , and is entirely overshadowed by lower/same tier/ higher tech like Artillery, Tanks, or Bombers/Nukes/Mech Inf. The Mall *is* pointless though.
Yeah why? The Numidian is a great improvement over HAs for cracking Spears or very high defenses (PRO archers). Arguably as good as the Keshik overall depending on terrain, definitely better specifically for breaking fortified positions or dealing with spears if you are too late cutting off metal. Nums are so slept on...don't underestimate free Flanking or the +melee combat power with Barracks for essentially 3 promos per unit out of the gate -- get a Stable too and that's C1 + Flanking + Shock (30% withdraw and -75% of that spear's +100% bonus) or C1 + Flanking 1 + Flanking 2 ( -50% of a spear's bonus and 50% withdraw!) en masse. They smoke Axes, in the open or defending in cities, like nobody's business too. Very good for HAs with no other support. Cothons meh for Hannibal though, better on EXP civ with Unrestricted Leaders.
Without going into each and every one, that B tier is overinflated. Based on Uniques alone Arabia, England, Korea, Vikings and Japan don't belong there (too high), Sumeria should definitely be in there and near the top of it if not in bottom of A, Zulu should be higher in that tier near Sumeria, etc.
EDIT: whoops I thought I saw Babylon in B, not C
:EDIT Also perplexing why Babylon in B but not Ottomans, who have better versions of both Uniques (earlier building combining health + happy and stronger resourceless defense unit) lol. And I think someone else pointed it out already, but Maya is pretty much = Native America based on Uniques alone, which means either Maya needs to go up or NA needs to come down to the other non-Inca guaranteed barb defenders (Maya, Mali, Babylon). The Dog is definitely the best of them and Bowman the worst, but the Totem is basically pointless while Ball Courts and Gardens aren't. Skirms are roughly the same as Holkans even if the Mint sucks. etc etc.
Here's a question: What are the UBs that objectively aren't great but you're fond of anyway?
Hammams and Dikes, similar to you. Dikes are just impressive sounding on paper (and the fact they can be built in any coastal city unlike Levees which require a river settle too helps) and appeal to min-maxing tendencies. I played an Ottoman game way back when where I did an Elepult attack with the Heroic Epic churning out an Elephant per turn in the capitol with Hammams whipped into outlier cites being slaved and I was thoroughly impressed by them.
Sorry didn't figure out how to directly quote in an edit