Spectacled Bear 
or
American Black Bear
- Both usable and would be great additions, but South America needs the rep and I also just prefer the distinct look of the Spectacled Bear.
Howler Monkey or
Hamadryas Baboon 
- Both good, but since I can get the Spider Monkey below at the loss of the GSNM which really isn't a loss at all, I would rather get the Spider which is my preferred choice and not lose the Baboon here to a species I'm indifferent to.
Coatimundi or
Tree Kangaroo 
- This one just comes down to personal preference, I know I said South America needs the rep but come on, I can't turn down a Tree Kangaroo.
Ocelot or
Pallas Cat 
- Pretty self expalantory, its either a small jaguar or a new species of cold climate cat and a small one at that, Pallas Cat low diff.
Greater Rhea 
or
Shoebill
- Not a huge fan of either, but I know the Rhea means more than the Shoebill to a lot of people and SA should probably get more rep than Africa so Rhea wins on a technicality.
Duck (any species) or
Pelican (any species) 
- Again personal preference, I prefer Pelicans over ducks because they give more opportunites to make enclosures for and I have more ideas for them than I would for a duck.
Walrus or
Muskox 
- Again dont really care about either, but if I have to choose then the Musk Ox just cause its a tad more useful (and when I say tad I mean I'll make an enclosure for it then I'm done with it, compared to the walrus which I wouldn't even touch.)
Markhor 
or
Blackbuck
- Both great and very usable, but I prefer the Markhor cause its a caprine and I enjoy building for goats, but the Blackbuck would probably represent Asia better.
Spider Monkey (any species) 
or
Golden Snub Nosed Monkey
- No explanation needed; The most energetic and unique species of primate vs one of the most boring imo
Patagonian Mara 
or
Rock Hyrax
- Both good, but South America needs rep and that alone just tips the scales.
Otter (Temperate Species) 
or
African Civet
- Interesting match up, I prefer the otter because we already have a lot of small carnivores from Africa (sand cat, caracal, fennec fox, etc) and getting the Sea Otter would give NA some rep and its pretty cool on its own.
Serval 
or
Racoon Dog
- I know I said we have a lot of African carnivores but.... Serval is the exception
Giraffe (second species) 
or
Zebra (second species)
- Both would be good add ins but Giraffes have more distinction from each other in appearance making them just slightly usable, plus we have a lot of better quality sub ins for a horse, kinda hard to find a high quality sub in for a Giraffe...
Elk or
Himalayan Tahr 
- Just a matter of personal preference on this one, I like caprines more than I do deer, maybe its too much getting this guy and the Markhor but not for me
Honey Badger 
or
Black Footed Ferret
- Ok one more exception to that rule about African carnivores...
Bat Eared Fox or
Bush Dog 
- More South America rep and its just a pretty cool species, it would fit nicely with the rest of smaller animals we have in the game.
Gelada 
or
Squirrel Monkey
- Very easy pick, I don't really like building for the really small primates and the squirrel monkey is one that really doesn't excite me, a majestic and fluffly Gelada on the other hand...
Brazilian Porcupine 
or
Aye Aye
- Oh porcupine 100%, such an amazing species, nothing else like it.
African Leopard or
Lion (second sub-group/Asiatic) 
- Don't really care about either of them but I guess the lion since it would be an upgrade to the base game one.
Numbat 
or
Brushtail Possum
- Numbat I guess? I couldn't care less about either of these so I'll just choose the one that looks cooler.