Have them both - use them both
I have both books. I use the Companion when teaching and working with groups that don't need a lot of information overload. It is useful, but I have found several mistakes. Can't remember exactly at the moment, but either the trigrams or the I Ching hexagrams come to mind. They printed two of one and none of another in the charts. I have noticed a couple of other questionable things in there. So I just remind folks that whatever their source, it was probably built on another source, and individuals should check their material and validate it before doing any fancy stuff.
Skinner's book, on the other hand, is most magnificent, and I am using it as a springboard for further study (LOVE his notes) and in my solitary practise. I believe Skinner went back to as many original sources as he could, and explained his logic in constructing the tables. I still validate and verify correspondences before I use them, but I feel a bit better using Skinner's stuff out of the box.
For what it's worth - I'm fairly eclectic, but I like my sources to dot their "i"s and cross their "t"s precisely. I break the rules all the time, but I want my books to be clear on what the rules are. If that makes any sense.
Happy Reading!
Mnem