It's getting to the point that buying all my favorite shows on iTunes and cancelling subscriptions to Netflix, Hulu, Amazon and the like is far easier. That way all my shows are in one place and I pay once, and not monthly which is milking me dry lately. A lot of my shows are older and are disappearing from streaming services anyway (such as Babylon 5 now 'unavailable' via Amazon, or Farscape disappearing from Netflix years ago, etc) and the only way I can keep enjoying them is by buying them outright.
Other streaming issues involve differences between sydication and original airing. Saved by the Bell is a good example of that. On the Hulu version, it stops at season 5 (which, according to the same show available via iTunes, is still season 3) when I remember watching the syndicated episodes back in 1996 that carried on for another season or two. There are scenes I recall that were absent from Hulu's version of the show, as well as differences in the theme intro music. On Apple TV, I've bought the complete series, which has a distinctly different intro music, which is a bit jarring but there are episodes missing or in the wrong season on Hulu that if I relied on it exclusively, I'd miss a ton of content. Saved By the Bell had a middle school and high school version, while Hulu treated the first two seasons (middle school) as if it didn't exist.
Hulu also has M*A*S*H but only 9 seasons of it from my end. It also doesn't include the series finale "Goodbye, Farewell, and Amen" which is unforgivable. I am glad I own the complete DVD set. All's there.