What is the best type bird for companionship with another female atiel?

I have a 3 year old female, 9 year old male and a newly adopted 10 year old male atiel. The female and male never bonded as mates but still liked each other. Now the 2 males are best buddies. I feel like the female is in need of more companionship. What would be the best type and gender of bird to get? I have a very large outdoor aviary and live in the south. I was thinking either a couple of parakeets or another female atiel. Advise anyone?