Always buy the disc, then rip
For one-off movies, we always just rent them. Everything else is streamed. But for those things that we (meaning "the kids") want to watch over and over, I buy the disc and then rip it. The thing about a ripped digital movie is that you can say "I want to watch this" and then watch it. If you use the disc, DVD or BlueRay, you have to suffer through endless unskippable crap, wait for what seems like an interminable amount of time before the snazzy menu comes up so you can hunt around on the DVD remote for the right key that plays the movie. Half the time you're treated to two more unskippable warnings from the FBI about doing the very thing you're thinking about, which is getting rid of this dumb crap you don't need to see every time you watch Wreck-It Ralph.
Compare that to open up Plex on the Roku box, use the world's simplest remote to navigate to what you want to watch, and then play it.
Attention Hollywood! I'm more than willing to pay for entertainment. I do not want to be given a wedgie every time I use your product though. Thanks!