How about another amazon?
It is much more likely (but not guaranteed, it is never guaranteed) that they will get along, so you won't have to get them separate cage time (which is very tiring in the long run...), and they can keep each other company when you humans can't be there.
Once there was a guy who had a grey and wanted to get a B&G, because the grey only wanted to be with his parents.
Other people thought he should get his grey a girlfriend instead, and one of them said "Would you rather have a girl in bed or a Proboscis monkey on the balcony?"
Unfortunately for this grey, he got the Proboscis monkey on the balcony.

But on a more serious note, getting your bird a friend of its own kind (yes I am looking for cagemates for my birds, but they are rare species and I have money trouble at the moment

) is about the best you can do for it. Studies have even proved that birds that have a partner live better lives and make better companions.
http://www.parrotchronicles.com/feature ... tstudy.htm