out of experience sun conures are the loudest of all the conures lol..
i woulnt reccomend one for a beginner or for apartment living..
if you want a quieter conure get a green cheeked conure.. they still scream if lonely, or if they want somthing.. but generally they are pretty quiet conures.. i love them, i have wanted one for over a year now, but i just dont have the time . good luck