1. Houston Zoo - I loved it both times I went there, it's a bit hard to explain why I like it so much, but I just do. Trust me on this one
2. St. Louis Zoo - Well, it was the first zoo I've ever been to, so nostalgia might play a part in my love for it, but I visit three times annually, and they always seem to be addig or renovating something (the most recent addition is the Tasmanian devil exhibit), which kind of amazes me, since admission to the zoo is free (but the city government does help pay for some stuff in the zoo, so it kinda makes sense).
3. Nashville Zoo - Though I was a bit disappointed as to the small size of the zoo when I first went last year, I can't hate it. There's so many cool exhibits it has, plus it's the first place I ever saw a tapir in person (they're my favorite animal, especially Lowland Tapirs), since the first time I went to Houston, the tapirs were off-display.
4. The Tulsa Zoo - My hometown zoo, so obviously this one deserves to have a spot on this list. The Tulsa zoo's nice, and its newer exhibits are some of the best I've ever seen or heard of for the animals that live in them. However, some parts of the zoo (the bear/lemur exhibits and the lion and tiger exhibits) are a bit outdated, although they're going to be renovated in the zoo's ten year 'master plan' (well, the tigers are going to be moved do Lost Kingdom: Tiger, along with the komodo dragons, the snow leopard, and the siamangs/ spectacled langurs).
5. The Oklahoma City Zoo - I've only been here twice, even though it's the second-closest zoo to where I live. I really don't like it that much; most of the exhibits are outdated. Just that simple fact. Half the exhibits were last renovated around 2005 (I'm just saying that, it might have been much more recent or much longer ago). Still, it's a decent zoo, but just not the best.
I haven't been to any of the zoos below
6. The Denver Zoo - The Denver Zoo is the one I'm going to next, since me and my family are stopping in Denver for a day on our way to Rocky Mountains National Park. There are tapirs there, and I've heard some pretty good things about it, so I'm pretty excited.
7. The LA Zoo - I guess now I'm listing them in the order of which one I'm visiting next XD Anyways, my brother reallyreallyreallyreallyreallyREALLY wants to go to E3 next year (that's a gaming convention, for anyone who doesn't know), so while we're in LA, we're also going to visit the zoo there (well, one of the zoos there

). I know next to nothing (try saying that five times fast) about the zoo, so I have no idea why I put it on here, besides that I'm excited for it.
8. Miami Zoo - I've heard quite a few good things about this zoo, and seeing a walkthrough video of it, this zoo seems pretty promising. I hope to go there in the next few years, because I cannot wait to see it for myself.
9. San Diego Zoo - Of COURSE I had to put this on here. I've only seen the map of the zoo, but for when I go, it looks pretty promising. They have Malayan tapirs, and plenty of other things, too. I really know nothing more about it. Yeah.