Um, one cockatoo is a lot to handle, having had both sulphur crested and Mollucan Cockatoos. Are you sure you want all that at once? They are very noisy and the dust gets everywhere. I loved my Moluccan, but the screaming was awful. And she bit my ear and made it bleed when she was on my shoulder. Now i can't wear an earring there until i get it pierced again. I have had birds since 1972. Sometimed less is better. Pionus are nice quiet birds.
Honestly I'm thinking the Pionus and the smaller cockatoo. They're part of a five bird flock with the larger cockatoo and 2 african greys.
I've had birds in tge past, not cockatoos or parrots though. Still thinking on it. Thanks for your input, it certainly helps to hear from experienced bird keepers!