In terms of the 170s, I think it depends on whether you're judging how suited for their routes they are. The 156s are too short, they're falling apart, and they are, by modern standards, unacceptably noisy inside. 170s are a much nicer environment for passengers, but they accelerate poorly, so they're badly suited to what Northern use them for.
I disagree that the 323 deserves to be anywhere other than on top, however. Despite being almost 30 years old now, a basic interior refurb has made it so that they still look, feel and sound modern, are reliable, and well-liked by passengers and staff. I once got chatting to a conductor on Northern who told me she'd rather work a 323 than either a 319 or a brand new 331! The only thing that lets them down is that the seats could do with more padding (and possibly reducing to 2+2 rather than 3+2) but I'm willing to give them a pass on that as the nature of their routes is such that most journeys are short.
I think I'd agree with that, except that given their reliability issues I would probably rank the 442 below the 158, 159 and 450.