[GDSOB]

Even identical houses in the same area can vary significantly. Some factors off the top of my head:

View
Corner lots - negative
Cul-de-sac lots - positive
Usable back yards - more is better
Traffic
Power lines
Neigbors
Proximity to lower valued or commercial properties

All this makes objective valuation just about impossible. I'm working with a buyer who is an engineer and is armed with spreadsheet covering every possible metric. But his wife has final approval and she could care less about his spreadsheets.