Assuming their domesticated enough to listen to my commands and ignore their pray drive, on like a magical level, Tiger. Hands down. I would go to the Renaissance Fair with them and commission a blacksmith to forge armor for them. I would ride it into battle whenever necessary.
Edit: I was also assuming no one else has a magically domestic animal. If everyone in this thread also has one, I’ll choose Rhinoceros
With those conditions I would pick a bear/panda or platypus respectively.
I’m pretty sure a Rhino would wreck any kind of bear, the only animal I think i would need to worry about is an elephant, would a platypus be able to penetrate a rhino’s skin?
Hear me out: a bear is useful, fuzzy and could probably squeeze through doors.
A platypus is just perfect, I don’t need it to have combat proweses when I can play with a platypus instead of fighting.
Being the only one with a bear would of course make fighting an option but still I wouldn’t want it to get hurt.
I like and really appreciate how you think. I definitely wouldn’t attack you with my Rhino, but I, personally, will not pick something that would leave me vulnerable against someone else who might. I hope you and your platypus-bear live in harmony🙏
Edit: but just so you know, a platypus wouldn’t leave you completely vulnerable, because they do have poisonous barbs. I’m not sure how effective those barbs are against large animals or humans, but I’m sure it would at least be a good deterrent