Also if planning remote outback travel diesel is easier to get hold of out there.
I struggled with this same question a couple of years ago. For us personally, we went for petrol (bought new). I have never had a diesel vehicle, so they are an unknown to me. After test driving the petrol i was happy with it, and after deciding we wanted a rubicon it settled it for us.
We are happy with our choice, however i do sometimes wonder what the diesel would have been like. I feel i should have at least driven one to compare... and with some mates talking about a simpson trip, i can certainly see advantages in the diesel.
However, i dont yet regret our choice, i just sometimes wonder.
Goid luck with whichever way you end up going