What is the best companion?

Hello to anybody who is reading this! I wanted to know what the best companion is so I can know which one to buy. Of course, donor ones look way better, so I am asking which is the best companion that you can buy in game and the best donor companion. If you would like to answer to this thread please use the following template:

Non donor
Best companion:
Pros:
Cons:

For example:

Donor
Best companion: Bunny
Pros: It gives you food
Cons: Little health

Thank you to anyone who...

What is the best companion?