Good question Rob.
I'm a bit obsessed with period correct groupset builds but also need my bikes to be very functional. I shy away from ultra-lightweight, fragile, boutique bling because I tried that BITD and most of it broke.
This has the added side effect or benefit that I'm rarely drawn to spending huge sums of money on individual parts or bikes. Thankfully.
So as well as a eye for durability and reliability, I usually have a strong leaning towards aesthetics especially where colour is concerned. I spend alot of attention on details like cable length/routing and crimps etc as well as lining up valves with tyre markings. The usual mild OCD stuff.
Ultimately I like to have period correct or period sensitive bikes which look good and perform well. Each bike has it's own subtle variations in keeping with it's character and original place in a range.
That is to say that, if it was originally a mid-range bike in 1993, I'll build it up as a mid range bike from 1993.
Personally I don't see the point of homogenising an old bike by building it up with modern parts.
I've enough modern bikes to fill those requirements.