In the spirit of full disclosure I must admit I may be biased, but my recommendation would be one of the red headed varieties (lilac crowned, red-lored, green cheeked/Mexican red head, lilacine, festive, etc). In my experience I have found them to be less hormonal when they mature (though every bird can be an exception to the generalization) and more even keeled in general with less highs and lows. My favorite being the Lilac Crown with a the Festive/Bodini being a close second. Of the group my Bodini amazon is the loudest in volume, but it could be because he thinks I spoil my Lilac Crown over him.
I would follow this group up with mealy amazon's but they are the largest of the amazons so space for a large enough cage would be a consideration with them. I have known a number of mealy amazons and found them all to be consistently more accepting of multiple people and again not has moody as their yellow feathered cousins. I have lived for a number of years with the other group (red-heads) so I am more confident in recommending them.