Getting my cat a cat!! Help!!

Hello!!

This is Menace, Menace is 11 months old and neutered.

I think he have only cat syndrome and there were many advices that getting him a sibling would help!

There’s two choices, a four months old kitten (not neutered, not vaccinated but is healthy) or a one and a half month old kitten, which one would be a better fit for him?