What are the opinions on these two books? It seems like there is more value and strong material in Card Classics. What do you think? Any ideas concerning Aronson's books? Which one (out of all of them) would be the one worth getting?

All the best!

My vote goes to Ken Krenzel's three books "The Card Classics of Ken Krenzel", "Ingenuities", and "Close-Up Impact!" because I always enjoyed his speciall brand of magic.
Many good and different effects can be found in these books.
If you like cardmagic you should get them.
All of them are equal good IMHO.
Highly recommended reading.

Peo

I have Ingenuities and must admit it is an interesting read and some of the effects will excite you. I must also admit however, that it's one of those books that I have liked but have not taken any usable material from. I still think it is a good book however.

The two books really can't be compared. Ingenuities has a focus of impromptu kind of self-working effects. Card Classics is some of the stuff Ken made famous due to his technique and presentation. I like both but for different reasons.

I would disagree with emeyers99 as there are many books that I have that I don't do any of the material. I have learned something from everyone of my books that his in some way made me a better magician. It might be an approach, a technique, a nuance to something. I think anybook you study will improve you as a magician and if you can get a routine or two out of it too, what a bonus!