I'm not too familiar with CATS, but for the other three i definitely agree that you should go with the original Broadway casts.
Much as I love the new orchestrations on the Encores! MERRILY WE ROLL ALONG, I always find myself going back to the original version. I just like some of the old material better, and the cast is great.
I didn't see the revival of MAN OF LA MANCHA, but for me that recording pales in comparison to the original, which is pretty much perfect. The performances on that album are so good I never miss the unrecorded material included on the other recording at all.
Like EricMontreal said, if you don't have the OBC of COMPANY you've got to get that. One of the best cast recordings ever.
Keeping BroadwayWorld Illustrated