As part of my upcoming travel plans I’m looking for any zoos in the US that are worth traveling to see. I know the San Diego zoo is highly regarded. IRC the Toledo Zoo has been world famous for a long time, I recall hearing about it when I was a kid even, but my online research seems to sugest that the Columbus Zoo is a lot better now.
As far as the worst, I’ll throw out the Minnesota Zoo. I actually like the Brutalist buildings, but it was built at a time when political correctness was in full swing. Originally they didn’t even call it a “zoo”. There’s no arguing that lions and tigers in cages was a bad thing, but the MN Zoo swung the other direction. Instead of lions and tigers there were beavers and lemurs, which you might see from a long distance away provided they weren’t hiding somewhere in their exhibit. The one marqee exhibit, the Beluga wales, went away years ago. The MN Zoo has gotten better but it’s still underwhelming IMHO.