I think they both get a bit boring after a while if you’re after watching films. They both have their exclusives, but after a few months, you’ve pretty much exhausted most of the films you’d want to watch. The TV series make it worth it. Just finished Breaking Bad, and just started Dexter on Netflix (I used to have lovefilm).
After I’ve done a couple more series, I’ll cancel it and leave it for 6 months or so and go back to one or the other, once they’ve built up a stock of new films.
I wouldn’t pay any more that £6 a month for either of them, though.