As someone who's played all 3 of these games, I'm hoping to give you an accurate description of them so that you can choose which is best for you.
First of all, Mope.io, the game this wikia is based off of. This is the first animal-based .io game I ever played.
PROS:
-Easy to chase prey, also croc, eagle and T. rex are good at fishing for water prey and dragging it on land. Croc can even do it with animals stronger than it.
-The bigger tier you are the easier it is to live. Gorilla is a good example of that, you can tease strong animals by throwing bananas in their face, and also give your team food by throwing bananas on the ground.
CONS:
-Hard to escape predators
-Eagles are literally everywhere and super annoying
-Chat is weird, (imo deeeep's chat is better) because you can't speak to people from way across the map like deeeep.io. You have to wander the entire map if you lose your teammate.
-Tailbiting is weird. You should be able to attack other animals no matter what their tier. A mouse is able to bite an elephant in real life for example. It would probably get trampled, but it still has that ability.
Okay, next up is Deeeep.io, I play this one a lot more often and (no offence to mope) like it more. However, that doesn't mean it has nothing bad about it, so here we go!
PROS:
-There's about a million different places to hide, and if you can't find one of them just boost away if you're in deep waters, or get to the surface and boost into the sky if you're in the arctic, swamp or normal water.
-Every animal is balanced. For example, Manatee, which eats crocs for breakfast even though croc is a higher tier, is slow as heck and can't boost.
CONS:
-If you're a tier 10, especially orca, there's a 'danger zone.' You'll see barely any orcas in the border between the deep and normal ocean, because there's always a giant squid lurking and ready to kill. Gsquid's only counter is cachalot, which is uncommon, so they take over the deep waters and kill everything in sight.
-The islands are completely coated in seagulls which attack everything. If you're unlucky enough to land on a populated island, whether you're a tier one or tier 10, you're going to be slaughtered.
And finally, creatur.io, the relatively new .io game. I haven't played this much so some of the facts may be a bit inaccurate, but I think I did a good job on this.
PROS:
-If you get the sprint ability, you can easily outrun anything. Wait for them to sprint after you, then sprint at the last second and you will always run for longer.
-Lots of easy kills.
CONS:
-The larger animals with the Dig ability are SUPER overpowered. In mope.io and deeeep.io, if an animal hides underground you can see it coming or run away after it bites you, respectively. On here, they're completely invisible. Combine this with the fact that creatures larger than you biting you is a 1 hit KO, makes them OP.
-Flight ability is also OP. I know, it doesn't last very long, but it's still way too fast. Literally nothing can kill you, and there's no downsides, unlike in Mope and Deeeep, where in mope you lose water extremely fast and have to find some before you land, and in deeeep all flying animals are weak, and easy prey to anything that can grab.
Hopefully you find out which of these .io games you like the best. I tried not to be biased to Deeeep, which I play like 5 times everyday.