I have a lvl 50 tiger that I ride around for hunting as well as for protecting my other tames. You might see me on the east side of k11 with both my elephant and tiger. Elephant for hauling, tiger for killing anything dangerous.
I think giraffes are supposed to be the fastest in terms of getting around.
Shoulder pets are also worth considering. Monkey flings poo and slows down attackers for you. Bunny makes a noise when predators are near. Crow gives intelligence buff. Parrots give fortitude buff.
You can have a shoulder pet and mount a larger pet at the same time.
Tigers are great for single target attacks, the jumping is great, and they have a bleed attack. I really think tigers are worth it.
I’m heading to k15 to get some penguins for their age hypothermic (hyper?) buff soon.
Breeding I haven’t really tried, but from what I have read seems terrible right now and not worth it.
Commands skills don’t seem to do anything either from what I can tell.
Domestic animals are ok for resources. Chickens give eggs, sheep give hide, cows milk. Horses are not worth it just because of how hard they are to bola. And they are just a fast mount, not for combat.