Blueray should be better quality, but I never got into bluerays. If you
already purhase things on iTunes, I think you'll find the best deal
there for digital content vs discs, and I doubt you'll have an issue
with the quality of the HD ones, unless you have a 4K TV, maybe. If you
have a poor internet connection, go the disc route.
I'll buy the original set from you; I have a CRT TV to watch it on ;)