I had both the Chris Henry book and the Bob Tait book when I studied it.
I found the Chris Hnery book an excellent resource. It is concise, has all the references to AIPs and Jepps and is also very good for prepping for renewal (it has a dedicated renewal section).
The Bob Tait book has a lot of VOR and NDB intercept (and other) exercises. It is targeted to those who are newer to IFR or less familiar with the flying theory.
Horses for courses i guess
Good luck
