Who should sponsor us?

[zacsmum]

My husbands parents live in Melbourne and so does his sister, but who should sponsor us?

My in-laws have a 2 bed unit and my sister in law a 3 bed big house, but she is a single mom with a teenage daughter.
Both familys earn around the same, just over 40k and both have one worker and one dependant.
Although my sister in law is obviously alot younger and my in laws are 3 years away from retireing. But my sister in law did have some visa problems and was thrown out of Oz 10 years ago but that is now sorted and she is now a full citizen. She is also in the process of buying a house for investment purposes.

I am so confused..... either can sponsor us..... but who is the safest bet.... who are the authoritys going to happily take and who will they question the ability to sponsor us?

Please help..... any advice appreciated!