Hi, welcome to BYC! 
 
 
I would get more EE, personally.
Orps, Rocks... all good.
My Wyandottes were NOT loud. But one of Lav Orps and an EE are the loudest girls ever... and it's great! But I have other EE and Orps that are quiet. And my bantam Silkie is right up there witht the loudest of them! I would say that more than anything... that is an individual characteristic more than typical, and I have 50 ish birds. No two are the same when it comes to noise level or friendliness.
Although I like Australorps and tried hard to finally get one... to me they will still be Orps which you already have and it is very nice to get a colorful basket. It can help you to determine if someone is having laying, nutritional, or health issues if you can tell the eggs apart easier. 

  Plus I feel like a big kid when I get to be surprised by what colors I get. 

  If you get EE that aren't flighty, they are super easy to handle or docile as people call it. I will NEVER have a flock without at least some EE.
Raising so many birds and getting rare breeds made me thinkl some of my others were... meh. But as they grow older, I still really like my barred rock and Orps and decided to let them stay even if everybody has them and they might be considered average. Thier personalities are far beyond average and they get so much better/calmer/friendlier after they have laid for a little while! (hens in general)