Share the ones you don't like, and share the ones you do! Is it worth it in the long run?
Rubinstein box: A treasure trove of great music making. Once I have listened to all of the discs, I will return to individual discs again and again for sheer enjoyment. I have always held Rubinstein in high regard, and this box simply increased his stature in my ears.
Casadesus Edition: Same as the Rubinstein box. My first giant box. I've owned it for over a decade, and never want to part with it.
DFD Schubert Lieder box: Same as Rubinstein and Casadesus.
Giulini boxes: Giulini is one of the greatest of all conductors, and even his weak recordings are worth hearing multiple times.
Karajan Symphony Edition: The right LvB cycle, the right Bruckner recordings, and Tchaikovsky. Will keep it for the strong ones, and not listen to the weak ones.
Scarlatti complete sonatas, Scott Ross: Brilliant! My second giant box, I bought it over a decade ago and I've listened to the entire thing thrice, and will do so again in the future.
Perahia box: A mixed bag, but enough good stuff to keep coming back to.
Cliburn box: Like Perahia.
Cortot box: So many indispensable recordings that it is destined to remain in my collection forever.
Francois box: Like Cortot.
Argerich boxes (DG/Decca): Almost like Rubinstein.
Graffman box: I'm only halfway through, and it is hit and miss, but the high points are so high that I will keep it since the great individual performances are not available separately.
Oistrakh box: Like Graffman.
Haydn string quartets, Angeles Quartet: Very good, and will keep it around until a better complete set is out there.
Sony Vivarte box: Like Perahia. (It was cheaper to buy the box than the roughly 10-12 individual recordings I really love.)
Haydn Symphonies, Fischer: Good, but not great. Will probably dispense with at some point.
Haydn Symphonies, DRD: Better, will probably keep.