I think you need to try to find out where the schools you are considering draw from (and how most kids get to them), and where kids "near" where you are typically go (and how they get there).
We grew up in Sydney; I was out of area for any of the zoned selectives (this was before they started expanding selective schooling again, which probably rather dates me now!), the only available option was a complex journey on public transport and my parents felt it was too far. DH was in an area where that school made sense. My sister and I both ended up on scholarships at independents. My journey door-to-door was about 3/4 hour which was less than many at my school. Her journey was a bit longer but also, changed timings significantly every time the train timetables were revised. She was perceived as "out of area" for her school even though others on slower transport routes took as long to get there; sometimes that created difficulties. Oh and most of our journey was on trains where we could often get work done.
As is often discussed on here, travelling independently is a huge life skill gained at secondary school so it would seem a shame to take on an option where that was impossible. But in rural areas all bets are off, I realise! Do the kids get permission to drive in yr 12 and is that likely to be an option for your family, given your child is at the older end of the yeargroup?
When do extracurricular activities run at each of these schools, what is your child likely to be interested in? Schools with a large cohort travelling significant distances may arrange more clubs etc during the school day rather than everything being after school, for example.
Kids who are a "tad quirky" deserve to be matched with a school that feels a better fit for them, if possible. Good luck figuring out a good solution and, since you have moved since your adult children were educated, don't let them prevent you choosing what this child needs.