I went to a catholic school, but religion was never forced on us. We had school masses and stuff, and you had to attend, but really thats no diffeent to being forced to attend school assemblies. Not everyone who went there was catholic, in fact, we had a fair few muslims, some non-religious ppl, some athiests and stuff (it was an all girls school) Some teachers were hard core catholics, but most were just average joe's, and the teachers beliefs never interfered with their teaching. We had to do Studies of religion for the HSC but that was learning about all religions and the connnections between then, it wasnt catholicism based.
I went to a public school as well for a while, but i think the catholic school was a much closer knit community, we had grade retreats and stuf, like camps, and we had pastoral care in homerooms so you got to mix with all the grades below you and stuff.
We also had a really active social justice network, but that wasnt necessarily because we were catholic, it was becasue we had some decent teachers who ran it.
I liked my Catholic school, but i wouldnt avoid public schools, like if there were no catholic schools in my area i would have gone to a public school, i dont have a problem with them. BTW, my school fees were only like $3000 a year, so it wasnt a fully private school, just non-public, if that makes sense.