I prefer Bun Bun because:
1) Bun Bun has a better sense of hygiene.
2) No problem in communication. Even they may pick up Cantonese first but you still need to break though the communication problem during at least 6 months. So if you are not a patient person, I think you better not to hire Yan Yan.
3) Most of the Yun Yun don't like Chinese people. If you treat them good, they think they deserve since Chinese people already robbed a lot of things from them in their country. If you treat them bad, they will also treat your child bad. Of course, there are always exception.
*In a word, they seldom appreciate what you have done to them.
4) Most of the Yun Yun is too young (16) even they don't know how to handle their own problem. Their government allow them to go to work from 16. Bun Bun 21. Go to victoria park on Sunday to take a look. All the maids there are Yun Yun. You may see so many tom boys hugging their partner, smoking etc.
Be fair, please also go to city hall to see the Bun Bun. Average they are older than Yun Yun, you may see them eating, chating, playing mahjong, even sleeping etc.
5) Before you make up your decision, please go to a kindergarten to take a look. You will find that most of the Bun Bun will pick up their child with a smiling face but Yun Yun not.
*I observed a long time in the school of my child.
5) You may also take a look in the transportation, you may find the same.
This is just my personal opinion, of course there are always exceptions. I think by visiting victoria park and city hall, you may get a better idea of their caracters.
Sorry I didn't read your content before posting the first message. By reading your topic, I thought you would like to ask whether Bun Bun is better or Yun Yun is better. Please kindly ignore my first message.
If you are urgent to find one, you may go to the agency on Sunday, you may find a lot of maids sitting there waiting for the employer. You may choose from them.
If you don't have any experience in hire the maid, I think you better though agency. It is safer.
If you don't want to hire though agency, it is easier if you hire bun bun. I also did it by myself.
I don't know about Yun Yun so I cannot say anything.