The irony that this thread was started by an op that was inherently snobby and is now being argued against by people being...snobby
As for what is classic/canon - even the academics and theorists can't agree on that! I did an assignment on that at uni, it's led to some quite heated arguments between certain theorists if I recall. In some cases they brought in some horrific prejudices to justify their claims eg God forbid a non-English non-White person write an incredible piece of literature!
Regarding classics are not as easy to read - to the contrary I've found several far easier to read than some popular/middle-low brow novels I've tried to read, in my case that particularly refers to Hilary mantel and Kathy Lette both of whom I'd expected to love. My experience at uni taught me not to judge a book by the blurb! I was dreading behind the scenes at the museum, waterland and passage to India (mum had watched the tv series and I'd hated it) yet when it came to it these became new favourite books and authors.
"I think sometimes the difference isn't in the books but in the attitude one brings to them" exactly - reader-response theory, the main reason most adaptations fail because each reader has imagined the characters, scenery, voices even equipment differently and partly why sue grafton was always adamant her work would not be adapted. Not even different readers but different mood/age/maturity in the same reader as several pp have noted.
As a teen I adored Jackie Collins and Jeffrey archer - not literary quality but bloody good storytelling. Let's face it (and I'm sure the pp publisher will back me up) even before kindle etc there are 1000's of books published if a book becomes a bestseller/popular it's not gong to be JUST because of advertising/hype (in fact I bet the publishers wish it were - would make their job easier) but because there is SOMETHING about it that appeals, a good plot, interesting even if unsympathetic characters, even appealing backdrops that draw the interest of readers.
Like I'm sure many teen girls of the era (80's) Jackie Collins' initial appeal was the 'rudey bits' but once you start reading them they are well paced and have some magnetic characters (which can be fun trying to work out who they're based on too).
Jeffrey archer my mum recommended as she knew I liked mysteries and twists, plenty of those in his books and not a penny more not a penny less appealed to my sense of justice and love of farcical crime capers.
However she also recommended Barbara Taylor Bradford who I couldn't bear due to the swathes of furnishing descriptions - but mum clearly loved that.
I went through a phase of reading Catherine Cookson but they are very clearly written to a formula so that grew boring fairly quickly BUT they're popular with some who may find that comforting.
In summary - each to their own - but don't judge others for their tastes (although as someone in the scene don't get me started on 50 shades crap! - purely as it concerns me it will lead to more women being abused - there are enough already!)