Bears are a curious case from me. Despite being one of my favorite animals i didn't used then after doing my first zoo ever. Meaning i never built properly for any of them.
But regardless, here's my ranking, from worst to best:
8 - HBB - We all agree on this, i don't really need to go over it.
7 - Formosan black bear - it... Exists. If im being honest im glad i used it in the past once in a badly build habitat, cause i don't see myself building for it.
6 - Giant Panda - this one is funny, Pandas would be one of the bears that i consider to be essential to be let out for any zoo game... And yet thanks to it status and lack of versatility i never really build for them.
In other words they are simply to unflexible and to famous to be anywhere higher.
5 - Polar bear - my favorite bear IRL that sadly suffers from the same problem as the Panda: i always want to build something spetacular for them which just takes to much time and effort considering this thing size requirement.
It's higher than the Panda by the simple facts that i like them more and they are slighlty more versatile.
4 - Sun bear - It's a "i didn't request you, but nonethless i'm happy you're here" situation.
It's a cool, unique looking and versatile animal with a great model. Nothing to complain here.
3 - Grizzly bear - not the best model, but it's so charismatic and versatile that leaving it anywhere else would be criminal.
2 - Sloth bear - it's a similar situation to the sun bear but higher thanks to how much i like it.
1 - spec bear - My boy, my beatiful boy!
I coudn't put the only south american bear and last short-face anywhere else in the list.
This is my second favorite bear and unlike polar, it has all the quality for a good animal: unique in usage, unique looking, unique taxonomically and a great animal nonethless.