Human :: 16 :: 86
Gorilla :: 9.1 :: 33
Chimp :: 6 :: 22
African Elephant :: 5.6 :: 251
Chimps are generally considered more intelligent than gorillas.
Bottlenose Dolphins have 11-15b cortical neurons while humans are in the range 14-18 (range is measurement uncertainty). It's also worth noting these dolphins have a larger brain mass (1.6 kg) and larger cortical surface (3700 cm2) than humans (1.3 kg and 2400 cm2, respectively).
> with no prehensile appendages, living in...
So more than scale. Glad we agree. Seems you also agree that architecture matters too.