Disc, but with a key that activates in steam/origin, so if the disc is lost or damaged, i still have a way of getting hold of the game.
The majority of UK ISP's aren't capable of giving speeds required to make downloading every game realistic, 22gb for rage, 16gb+ for witcher 2, 32gb for GT4 + EFLC etc...I can't sit for 10 hours to download a game when I could just pop a disc in and have it installed in 20mins.
Until we shed this horrible 'upto' attitude from ISP's, and they start making an effort to put the technology in place to improve connection speeds (I'm looking at your sky, your supposed LLU line that gives 5mb of a 20mb connection), I'm still going to be for the most part buying discs.
If your lucky enough to live in say, a cable area, or infinity area, then (as I would in that situation) I'd download everything.