It depends on what your needs are in the long run and your child's personality. I don't know what Victoria is like and can only gather that it is popular with mums who want their children to become effective bilinguals (but there is a debate there).
We chose ESF (in comparison to two other international school options) because
(1) of their IB programme in primary school. Didn't want to miss out the opportunity on not getting into an ESF school. The other IB schools were more expensive and when you compare the staff student ratio (not particularly interested in small class sizes because we don't think our son needs to be in a small class size), number of ESL students, facilities, it made very little difference.
(2) in terms of funding, ESF is well funded so I'm presuming in terms of infrastructure, we had more faith in ESF (despite not having an indoor swimming pool/tennis courts/ etc. - not an important criteria when you live in an apartment complex that has one!) - I'm more concerned about ICT and classroom facilities.
(3) hires only trained teachers. I've seen ads for other schools that don't require QKT or they say they do and end up hiring a Causasion (sometimes for the "Anglo looking" factor and not even from an English speaking country) - I don't care if my son's teacher is black, brown or blue, I only care that he is in the hands of a qualified and capable educator.
(4) ESF offers lots of extra-curricular programmes.
(5) For the 24 kids in a class, there is a main teacher and two teaching assistants (not counting parent volunteers) - Most schools have 24 kids with one teaching assistant. Teacher turnover is not a problem. Good balance of experienced and beginner teachers.
(6) There is a local feel to ESF that we like which balances out the international needs well.
(7) Good mix of students.
(8) Apart from the complaint that "there is just too many ESL kids at ESF", we have not heard anything particularly bad about ESF. In the words of Marty the zebra (from Madagascar) to the penguins, "I spreaken English" i.e. English is not an ESL for us so it's immaterial.

ESF has a strict English policy. I have a colleague who is a product of a popular international school that cannot construct a good English sentence as he says that although these schools claim to be an "international school", Cantonese is still a dominant language of communication as it was just easier. All my friends who attended ESF are not ESL speakers for sure.