Post Punk is quite simply the bands that made music after 1978 who could actually play and/or conceptualise music but used the raw energy of Punk to give it focus.

Siouxsie and the Banshees debut The Scream is a brilliant example. It's not a Punk album but it's abrasive enough to be included yet it sounds nothing like the bands around the time. Gets my vote every time.

well, post-rock covers:-

Slint's Spiderland - which is more "mathy"
Talk Talk's last 2 albums - more jazzy/classical
Godspeed You! Black Emperor - lengthy prog-like pieces
Sigur Ros - eclectic and closer to "Shoegaze" or "dream-pop"

I vote for Unknown Pleasures

Wipers - Over the Edge by miles for me...has an amazing atmosphere and is consistent from start to finish.

Not in anyway the case. The only reason it might seem like this, is because post punk influenced bands are often called post punk when they are just alt rock. Look at Joy Division, early Cocteau Twins, Early Sonic Youth, Jesus and Marry Chain, Gang of Four, and Public Image ltd. They all have a stylistic similarity not shared by bands not considered post punk. It is as defined a style as punk rock itself, and many post punk acts crossover into new wave which is pretty much post punk + synth pop. This crossover is a large reason for the confusion I think.

New Wave was the major labels attempt at commercialising what was left of the punk influence.

Post punk was virtually the opposite of that, I don't see there's any crossover at all.

I take it you haven't listened to a This Heat album. Makes The Ramones sound like Cilla Black.

As for best album... Metal Box, Pink Flag or Jane From Occupied Europe, it depends on my mood.

Metal Box isn't that accessible, either

well, not on initial listens

"Flowers of Romance" was also pretty difficult to get into

My point was that, generally, post-punk isn't more accessible than punk. I wasn't going to sit there listing all the albums that make punk sound tame, I'd be at it for days.

I quite like Adam and the Ants's 'dirk wears white sox'.

And yes, that 'flowers of romance' is difficult, with a strong tribal dimension, just like many other albums of that time (KJ's 'fire dances', The Cure's 'Pornography', Virgin Prunes' 'a new form of beauty'...).