Smallville is a poor mans Buffy.
Nearly everything they do is stolen from that or other shows.
Characters don't grow and nothing is ever really resolved.
They also resort to nonsensical rubbish to keep characters like Lana and Lionel in the show.
The writers seem to think Chloe is veronica mars and give her the most annoying dialog you will ever hear.
Lastly, the whole "is he good or evil" dance they do with Lex got old after the first few years and perhaps epitomizes the greater problem of over doing an idea and not moving forward.
That being said, I still watch it because louise lane is hot.
Supernatural is a little shallow perhaps but is great fun.
It doesn't take itself too seriously and Dean is very funny.
Its by far the more enjoyable show.