There's a great deal of canon in the movies. And I know more people who went from the movies to the books than from the BBC series to the books.

Me, I've been a Sherlockian for decades, and I love them both. And Granada. And the Russian series. And the Ronald Howard series. And for that matter the Geoffrey Whitehead... er, um, yup, as long as there's a decent Watson, I'm pretty much a fan!