I'll give it a go:
1. Africa - Pretty good scenery but the pack is filled with essential zoo animals with arguably the strongest roster of any pack, I don't think there is anything I would change about this pack
2. Conservation - Very useful scenery and again a strong roster of key animals, the pack also introduced brachiation and Gibbons which are my favourite animals so maybe some slight bias
3. Grasslands - The best animal pack with a very diverse range of animals from all around the world, gave SA and Australia a boost and also wasn't very ungulate heavy, I like all the picks especially the Maned Wolf, although I would have swapped the Hyena out for a different animal such as the Grey Crowned Crane
4. Aquatic - This pack has wonderful scenery and at the time the animals were revolutionary, however I think the pack hasn't aged incredibly due to some better alternatives such as the Sea Lion and African Penguin although I still prefer the Giant Otter
5. SA - The scenery is very heavily themed but some pieces are useful, some of the animals (Jaguar, Anteater) are essential, however I am still a bit upset that the Llama and Capuchin weren't a Guanaco and Squirrel Monkey, the pack is helped by how desolate SA is which may cause it to drop in future
6. Wetlands - Some wonderful animal choices such as the Capybara and Otter, however some are misses, if we were getting a water buffalo it should have been domestic and I feel the pack missed the chance to add more wading birds such as the Marabou Stork or Shoebill
7. Australia - Pretty good scenery and a nearly perfect roster (Dingo)
8. North America - Some great choices of animals like the Moose and Sea Lion and others that I don't like as much but are also essential for representing certain groups (Beaver and Prairie Dog for rodents)
9. Europe - Wonderful scenery but the animals are a bit of a let down for me (Yes, I am European) I think the Lynx and Deer are great, the Ibex ok and the badger was one of the worst picks possible, I would have much rather had the Wild Boar or Wolverine instead
10. SEA - The pack has definitely gotten better over time as it has been retroactively been fixed although it was a bit of a stinker at launch, I think all the animal choices are good except the Proboscis Monkey should have been a different Primate, the ideal situation would be a Gibbon but that's not realistic, I think the Francois' Langur would have worked a lot better instead
11. Tropical - Good scenery, the animal choices are a bit of a mess, the Red River Hog and Fossa are great animals but for a scenery pack with limited slots probably not the best choices, the Lar Gibbon gets some points for being my preferred species of Gibbon and having much better brachiation but this should have been the Spider Monkey alongside a Siamang remaster, the Asian Water Monitor is just a Nile Monitor remaster but it doesn't even have deepdiving so feels really weird for me, this pack had so much potential but it was wasted, definitely should have been an animal pack where it had the potential for an incredible roster
12. Eurasia - So mixed on this pack, I think the Wolverine, Boar, Swan and Takin were great choices, the Wisent is nice but I think I would have preferred a Bison remaster (again as a European), the Sloth Bear is ok but could've been something else and fills a very similar niche to the Sun Bear, then there is the Saiga (should've been the Muntjac or Blackbuck)
13. Oceania - The scenery is pretty nice and I like the vibe of it, the animals are a pretty good Oceania roster, but some of them don't really do anything for me (Quokka, Penguin), I mean they are nice editions but I'm just not the right audience, although I am a big fan of the Kiwi and Devil
14. Twilight - Some of the pieces are overly themed so are a bit useless for me but others are good, the animals are ok there were definitely much better picks available like the Fossa, Tasmanian Devil or Kiwi, the walkthrough is ok, I don't personally use it and I think it feels a bit out of place (the same sentiment applies to all the walkthrough species)
15. Arid - The Porcupine is great although I would trade it for the rest of the pack being better, the Dromedary is the only other animal I think should have made the pack (actually maybe the Somali Wild Ass as well), the rest of the pack is just boring for me, the wrong antelopes, the wrong cat and another Rhino, there were so many better options like the Baboon, Honey Badger, Tortoise and countless birds this pack also had potential for greatness but left me wanting another African animal pack immediately as it kinda failed at its task
16. Arctic - Ok scenery, two great animals in the Polar bear and Reindeer, one alright animal in the Dall Sheep and then there is the Arctic Wolf
17. Barnyard - Pieces are good and I quite like this potential knew format (although I suspect it was a one off), the animals are mixed, I wasn't a great fan of domestics and they chose some odd breeds as well as some weird misses (Duck, Rabbit), overall I think the hate for the pack is overblown but I agree with many people's points on it, the timing is somewhat unfortunate with fears of the end and a very Ungulate heavy year as well as a Europe centric pack after a Eurasian pack