I used to have a mixture of 12v grey and 4.5v blue when I was a kid. I didn't have enough 12v to motorise more than a small section of temporary layout so I pretty much resorted to building push trains. I only had one motor and transformer also- my points were 4.5 volts and I had none of the other accessories.
But 12v really does have a sense of magic for me- I remember the sheer quality of the engineering- even the cardboard boxes were well made! 9v seems to have been a little bit of a step backwards in regard to playability. And from what I can tell from forum posts, TLG don't appear to have made it particularly easy to motorise 9v and later points, which seems a shame. My fantasy Lego train layout (to go in my fantasy Lego house!) would probably be a hybrid 9v-PF DCC system- assuming its possible to kit-bash some kind of pickup system.
12v though- back in the day this system was far and above anything else in the toyshop in terms of desirability and quality as far as I was concerned. Apart from playability everything else looked cheap and tacky by comparison- a bit like comparing a 1980s Mercedes S Class (back when Mercedes quality was unimpeachable) to a Russian Lada!